diff --git a/app/Http/Controllers/Api/V1/TimeEntryController.php b/app/Http/Controllers/Api/V1/TimeEntryController.php
index 75641fea..be6eb519 100644
--- a/app/Http/Controllers/Api/V1/TimeEntryController.php
+++ b/app/Http/Controllers/Api/V1/TimeEntryController.php
@@ -535,7 +535,7 @@ class TimeEntryController extends Controller
                 ->putFileAs($folderPath, new File($tempFolder->path($filenameTemp)), $filename);
         } else {
             Excel::store(
-                new TimeEntriesReportExport($aggregatedData, $format, $currency, $group, $subGroup, $showBillableRate),
+                new TimeEntriesReportExport($aggregatedData, $format, $currency, $group, $subGroup, $showBillableRate, $localizationService),
                 $path,
                 config('filesystems.private'),
                 $format->getExportPackageType(),
diff --git a/app/Service/LocalizationService.php b/app/Service/LocalizationService.php
index a03d1b7d..bee7490a 100644
--- a/app/Service/LocalizationService.php
+++ b/app/Service/LocalizationService.php
@@ -8,12 +8,14 @@ use App\Enums\CurrencyFormat;
 use App\Enums\DateFormat;
 use App\Enums\IntervalFormat;
 use App\Enums\NumberFormat;
+use App\Enums\TimeEntryAggregationType;
 use App\Enums\TimeFormat;
 use App\Models\Organization;
 use Brick\Math\BigDecimal;
 use Brick\Money\Money;
 use Carbon\CarbonInterface;
 use Carbon\CarbonInterval;
+use Illuminate\Support\Carbon;
 
 class LocalizationService
 {
@@ -152,6 +154,29 @@ class LocalizationService
         return $date->format($this->dateFormat->toCarbonFormat());
     }
 
+    /**
+     * Time group types have no server-side descriptor, so reports fall back to rendering the raw
+     * aggregation key. For the Day type that key is an ISO date (Y-m-d), which is formatted here
+     * so exports match the rest of the UI instead of leaking the key.
+     *
+     * Week, month and year keys have different shapes ('Y-m-d' for the week start, 'Y-m' and 'Y'),
+     * and are not offered as a grouping in the reporting UI, so they are returned unchanged.
+     * Presenting those needs its own decision: a week rendered as its start date reads as a single
+     * day, and a month rendered with a full date format reads as a specific day.
+     */
+    public function formatTimeGroupKey(?string $key, TimeEntryAggregationType $groupType): ?string
+    {
+        if ($key === null) {
+            return null;
+        }
+
+        if ($groupType !== TimeEntryAggregationType::Day) {
+            return $key;
+        }
+
+        return $this->formatDate(Carbon::parse($key));
+    }
+
     public function setDateFormat(DateFormat $dateFormat): void
     {
         $this->dateFormat = $dateFormat;
diff --git a/app/Service/ReportExport/TimeEntriesReportExport.php b/app/Service/ReportExport/TimeEntriesReportExport.php
index 5b6f3048..3ae6e5ea 100644
--- a/app/Service/ReportExport/TimeEntriesReportExport.php
+++ b/app/Service/ReportExport/TimeEntriesReportExport.php
@@ -6,6 +6,7 @@ namespace App\Service\ReportExport;
 
 use App\Enums\ExportFormat;
 use App\Enums\TimeEntryAggregationType;
+use App\Service\LocalizationService;
 use Illuminate\View\View;
 use Maatwebsite\Excel\Concerns\Exportable;
 use Maatwebsite\Excel\Concerns\FromView;
@@ -48,6 +49,8 @@ class TimeEntriesReportExport implements FromView, ShouldAutoSize, WithCustomCsv
 
     private bool $showBillableRate;
 
+    private LocalizationService $localization;
+
     /**
      * @param array{
      *         grouped_type: string|null,
@@ -68,7 +71,7 @@ class TimeEntriesReportExport implements FromView, ShouldAutoSize, WithCustomCsv
      *         cost: int|null
      *   } $data
      */
-    public function __construct(array $data, ExportFormat $exportFormat, string $currency, TimeEntryAggregationType $group, TimeEntryAggregationType $subGroup, bool $showBillableRate)
+    public function __construct(array $data, ExportFormat $exportFormat, string $currency, TimeEntryAggregationType $group, TimeEntryAggregationType $subGroup, bool $showBillableRate, LocalizationService $localization)
     {
         $this->data = $data;
         $this->exportFormat = $exportFormat;
@@ -76,6 +79,7 @@ class TimeEntriesReportExport implements FromView, ShouldAutoSize, WithCustomCsv
         $this->group = $group;
         $this->subGroup = $subGroup;
         $this->showBillableRate = $showBillableRate;
+        $this->localization = $localization;
     }
 
     public function view(): View
@@ -87,6 +91,7 @@ class TimeEntriesReportExport implements FromView, ShouldAutoSize, WithCustomCsv
             'subGroup' => $this->subGroup,
             'exportFormat' => $this->exportFormat,
             'showBillableRate' => $this->showBillableRate,
+            'localization' => $this->localization,
         ]);
     }
 
diff --git a/resources/views/reports/time-entry-aggregate/pdf.blade.php b/resources/views/reports/time-entry-aggregate/pdf.blade.php
index 4681cf83..9fc4472e 100644
--- a/resources/views/reports/time-entry-aggregate/pdf.blade.php
+++ b/resources/views/reports/time-entry-aggregate/pdf.blade.php
@@ -194,7 +194,7 @@
                                 @if($group->is(\App\Enums\TimeEntryAggregationType::Billable))
                                     {{ $group1Entry['key'] === '1' ? 'Billable' : 'Non-billable' }}
                                 @else
-                                    {{ $group1Entry['description'] ?? $group1Entry['key'] ?? 'No '.Str::lower($group->description()) }}
+                                    {{ $group1Entry['description'] ?? $localization->formatTimeGroupKey($group1Entry['key'], $group) ?? 'No '.Str::lower($group->description()) }}
                                 @endif
                             </span>
                         </td>
@@ -239,7 +239,7 @@
                 <span style="color: #a1a1aa;">
                     {{ $group->description() }}:
                     </span>
-                {{ $group1Entry['description'] ?? $group1Entry['key'] ?? 'No '.Str::lower($group->description()) }}
+                {{ $group1Entry['description'] ?? $localization->formatTimeGroupKey($group1Entry['key'], $group) ?? 'No '.Str::lower($group->description()) }}
             @endif
         </h2>
 
@@ -278,7 +278,7 @@
                             @if($subGroup->is(\App\Enums\TimeEntryAggregationType::Billable))
                                 {{ $group2Entry['key'] === '1' ? 'Billable' : 'Non-billable' }}
                             @else
-                                {{ $group2Entry['description'] ?? $group2Entry['key'] ?? '-' }}
+                                {{ $group2Entry['description'] ?? $localization->formatTimeGroupKey($group2Entry['key'], $subGroup) ?? '-' }}
                             @endif
                         </td>
                         <td>
@@ -318,7 +318,7 @@
 
         series: [
             {
-                data: {!! json_encode(collect($aggregatedData['grouped_data'])->map(function (array $data) use (&$colorService, $group): object {
+                data: {!! json_encode(collect($aggregatedData['grouped_data'])->map(function (array $data) use (&$colorService, $group, $localization): object {
                     $color = $data['color'];
                     if ($color === null) {
                         $color = $colorService->getRandomColor($data['key']);
@@ -328,7 +328,7 @@
                     }
                     return (object)[
                         'value' => $data['seconds'],
-                        'name' => $data['description'] ?? $data['key'] ?? 'No '.Str::lower($group->description()),
+                        'name' => $data['description'] ?? $localization->formatTimeGroupKey($data['key'], $group) ?? 'No '.Str::lower($group->description()),
                         'color' => $color,
                         'itemStyle' => (object) [
                             'color' => $color,
diff --git a/resources/views/reports/time-entry-aggregate/spreadsheet.blade.php b/resources/views/reports/time-entry-aggregate/spreadsheet.blade.php
index 18e152ca..0dd514b2 100644
--- a/resources/views/reports/time-entry-aggregate/spreadsheet.blade.php
+++ b/resources/views/reports/time-entry-aggregate/spreadsheet.blade.php
@@ -44,7 +44,7 @@
                         </td>
                     @else
                         <td style="border: 1px solid black;" data-type="{{ DataType::TYPE_STRING }}">
-                            {{ $group1Entry['description'] ?? $group1Entry['key'] ?? '-' }}
+                            {{ $group1Entry['description'] ?? $localization->formatTimeGroupKey($group1Entry['key'], $group) ?? '-' }}
                         </td>
                     @endif
                     @if ($subGroup === TimeEntryAggregationType::Billable)
@@ -53,7 +53,7 @@
                         </td>
                     @else
                         <td style="border: 1px solid black;" data-type="{{ DataType::TYPE_STRING }}">
-                            {{ $group2Entry['description'] ?? $group2Entry['key'] ?? '-' }}
+                            {{ $group2Entry['description'] ?? $localization->formatTimeGroupKey($group2Entry['key'], $subGroup) ?? '-' }}
                         </td>
                     @endif
                     <td style="border: 1px solid black;" data-type="{{ DataType::TYPE_STRING }}">
@@ -74,7 +74,7 @@
                         </td>
                     @else
                         <td style="border: 1px solid black;" data-type="{{ DataType::TYPE_STRING }}">
-                            {{ $group1Entry['description'] ?? $group1Entry['key'] ?? '-' }}
+                            {{ $group1Entry['description'] ?? $localization->formatTimeGroupKey($group1Entry['key'], $group) ?? '-' }}
                         </td>
                     @endif
                     @if ($subGroup === TimeEntryAggregationType::Billable)
@@ -83,7 +83,7 @@
                         </td>
                     @else
                         <td style="border: 1px solid black;" data-type="{{ DataType::TYPE_STRING }}">
-                            {{ $group2Entry['description'] ?? $group2Entry['key'] ?? '-' }}
+                            {{ $group2Entry['description'] ?? $localization->formatTimeGroupKey($group2Entry['key'], $subGroup) ?? '-' }}
                         </td>
                     @endif
                     <td style="border: 1px solid black;" data-type="{{ DataType::TYPE_NUMERIC }}"
diff --git a/tests/Unit/Endpoint/Api/V1/TimeEntryEndpointTest.php b/tests/Unit/Endpoint/Api/V1/TimeEntryEndpointTest.php
index b8f18bc6..a6eff697 100644
--- a/tests/Unit/Endpoint/Api/V1/TimeEntryEndpointTest.php
+++ b/tests/Unit/Endpoint/Api/V1/TimeEntryEndpointTest.php
@@ -4,6 +4,7 @@ declare(strict_types=1);
 
 namespace Tests\Unit\Endpoint\Api\V1;
 
+use App\Enums\DateFormat;
 use App\Enums\ExportFormat;
 use App\Enums\Role;
 use App\Enums\TagMatchType;
@@ -1641,6 +1642,106 @@ class TimeEntryEndpointTest extends ApiEndpointTestAbstract
         $this->assertResponseCode($response, 200);
     }
 
+    public function test_aggregate_export_endpoints_can_create_a_pdf_report_grouped_by_date(): void
+    {
+        // Arrange
+        $data = $this->createUserWithPermission([
+            'time-entries:view:all',
+        ]);
+        $client = Client::factory()->forOrganization($data->organization)->create();
+        $project = Project::factory()->forOrganization($data->organization)->forClient($client)->create();
+        $timeEntry1 = TimeEntry::factory()->forOrganization($data->organization)->forMember($data->member)->startWithDuration(Carbon::now(), 100)->create();
+        $timeEntry2 = TimeEntry::factory()->forOrganization($data->organization)->forProject($project)->forMember($data->member)->startWithDuration(Carbon::now(), 100)->create();
+        Passport::actingAs($data->user);
+        $this->actAsOrganizationWithSubscription();
+
+        // Act
+        $response = $this->getJson(route('api.v1.time-entries.aggregate-export', [
+            $data->organization->getKey(),
+            'format' => ExportFormat::PDF,
+            'group' => TimeEntryAggregationType::Day,
+            'sub_group' => TimeEntryAggregationType::Project,
+            'history_group' => TimeEntryAggregationTypeInterval::Day,
+            'start' => Carbon::now()->startOfYear()->toIso8601ZuluString(),
+            'end' => Carbon::now()->endOfYear()->toIso8601ZuluString(),
+        ]));
+
+        // Assert
+        $this->assertResponseCode($response, 200);
+    }
+
+    public function test_aggregate_export_pdf_renders_date_group_labels_in_organization_date_format(): void
+    {
+        // Arrange
+        $this->travelTo(Carbon::create(2024, 3, 15, 12, 0, 0, 'UTC'));
+        $data = $this->createUserWithPermission([
+            'time-entries:view:all',
+        ]);
+        // Note: the organization factory randomizes the date format, so pin it
+        $data->organization->update(['date_format' => DateFormat::SlashSeparatedDDMMYYYY]);
+        $project = Project::factory()->forOrganization($data->organization)->create();
+        TimeEntry::factory()->forOrganization($data->organization)->forProject($project)->forMember($data->member)
+            ->startWithDuration(Carbon::now()->subDay(), 3600)->create();
+        Passport::actingAs($data->user);
+        $this->actAsOrganizationWithSubscription();
+
+        // Act
+        // Note: debug=true returns the rendered HTML instead of handing it to the PDF renderer.
+        $response = $this->getJson(route('api.v1.time-entries.aggregate-export', [
+            $data->organization->getKey(),
+            'format' => ExportFormat::PDF,
+            'group' => TimeEntryAggregationType::Day,
+            'sub_group' => TimeEntryAggregationType::Project,
+            'history_group' => TimeEntryAggregationTypeInterval::Day,
+            'start' => Carbon::now()->subDays(7)->toIso8601ZuluString(),
+            'end' => Carbon::now()->toIso8601ZuluString(),
+            'debug' => 'true',
+        ]));
+
+        // Assert
+        $this->assertResponseCode($response, 200);
+        $html = $response->json('html');
+        $this->assertIsString($html);
+        $this->assertStringContainsString('14/03/2024', $html);
+        $this->assertStringNotContainsString('2024-03-14', $html);
+    }
+
+    public function test_aggregate_export_csv_renders_date_group_labels_in_organization_date_format(): void
+    {
+        // Arrange
+        $this->travelTo(Carbon::create(2024, 3, 15, 12, 0, 0, 'UTC'));
+        $data = $this->createUserWithPermission([
+            'time-entries:view:all',
+        ]);
+        // Note: the organization factory randomizes the date format, so pin it
+        $data->organization->update(['date_format' => DateFormat::SlashSeparatedDDMMYYYY]);
+        $project = Project::factory()->forOrganization($data->organization)->create();
+        TimeEntry::factory()->forOrganization($data->organization)->forProject($project)->forMember($data->member)
+            ->startWithDuration(Carbon::now()->subDay(), 3600)->create();
+        Passport::actingAs($data->user);
+
+        // Act
+        $response = $this->getJson(route('api.v1.time-entries.aggregate-export', [
+            $data->organization->getKey(),
+            'format' => ExportFormat::CSV,
+            'group' => TimeEntryAggregationType::Day,
+            'sub_group' => TimeEntryAggregationType::Project,
+            'history_group' => TimeEntryAggregationTypeInterval::Day,
+            'start' => Carbon::now()->subDays(7)->toIso8601ZuluString(),
+            'end' => Carbon::now()->toIso8601ZuluString(),
+        ]));
+
+        // Assert
+        $this->assertResponseCode($response, 200);
+        $disk = Storage::disk(config('filesystems.private'));
+        $files = $disk->files('exports');
+        $this->assertCount(1, $files);
+        $csv = $disk->get($files[0]);
+        $this->assertIsString($csv);
+        $this->assertStringContainsString('14/03/2024', $csv);
+        $this->assertStringNotContainsString('2024-03-14', $csv);
+    }
+
     public function test_index_export_endpoint_with_client_ids_filter_returns_filtered_entries(): void
     {
         // Arrange
diff --git a/tests/Unit/Service/LocalizationServiceTest.php b/tests/Unit/Service/LocalizationServiceTest.php
index 8904eebe..ea601fba 100644
--- a/tests/Unit/Service/LocalizationServiceTest.php
+++ b/tests/Unit/Service/LocalizationServiceTest.php
@@ -8,6 +8,7 @@ use App\Enums\CurrencyFormat;
 use App\Enums\DateFormat;
 use App\Enums\IntervalFormat;
 use App\Enums\NumberFormat;
+use App\Enums\TimeEntryAggregationType;
 use App\Enums\TimeFormat;
 use App\Service\LocalizationService;
 use Brick\Money\Currency;
@@ -303,4 +304,39 @@ class LocalizationServiceTest extends TestCaseWithDatabase
         // Assert
         $this->assertSame('14:09', $formatted);
     }
+
+    public function test_format_time_group_key_formats_a_day_key_with_the_date_format(): void
+    {
+        // Arrange
+        $this->localizationService->setDateFormat(DateFormat::SlashSeparatedDDMMYYYY);
+
+        // Act
+        $formatted = $this->localizationService->formatTimeGroupKey('2001-02-03', TimeEntryAggregationType::Day);
+
+        // Assert
+        $this->assertSame('03/02/2001', $formatted);
+    }
+
+    public function test_format_time_group_key_returns_null_for_a_null_key(): void
+    {
+        // Act
+        $formatted = $this->localizationService->formatTimeGroupKey(null, TimeEntryAggregationType::Day);
+
+        // Assert
+        $this->assertNull($formatted);
+    }
+
+    public function test_format_time_group_key_returns_the_key_unchanged_for_non_day_group_types(): void
+    {
+        // Arrange
+        $this->localizationService->setDateFormat(DateFormat::SlashSeparatedDDMMYYYY);
+
+        // Act & Assert
+        // Week/month/year are not offered as a grouping in the reporting UI and their keys have
+        // different shapes, so they are passed through rather than formatted as a date.
+        $this->assertSame('2001-02-03', $this->localizationService->formatTimeGroupKey('2001-02-03', TimeEntryAggregationType::Week));
+        $this->assertSame('2001-02', $this->localizationService->formatTimeGroupKey('2001-02', TimeEntryAggregationType::Month));
+        $this->assertSame('2001', $this->localizationService->formatTimeGroupKey('2001', TimeEntryAggregationType::Year));
+        $this->assertSame('some-uuid', $this->localizationService->formatTimeGroupKey('some-uuid', TimeEntryAggregationType::Project));
+    }
 }