diff --git a/app/Domains/Catalog/Models/Variant.php b/app/Domains/Catalog/Models/Variant.php
index 71016ca..147c449 100644
--- a/app/Domains/Catalog/Models/Variant.php
+++ b/app/Domains/Catalog/Models/Variant.php
@@ -109,10 +109,23 @@ class Variant extends Model
     public function selectionValues(): Collection
     {
         $values = $this->definitions
-            ->mapWithKeys(fn ($definition) => [
-                $definition->itemAttribute?->attribute?->codigo => $definition->value,
-            ])
-            ->filter(fn ($value, $key): bool => $key !== null);
+            ->groupBy('item_attribute_id')
+            ->mapWithKeys(function (Collection $definitions): array {
+                $itemAttribute = $definitions->first()?->itemAttribute;
+                $attributeCode = $itemAttribute?->attribute?->codigo;
+
+                if ($attributeCode === null) {
+                    return [];
+                }
+
+                $definitionValues = $definitions->pluck('value')->values();
+
+                return [
+                    $attributeCode => $itemAttribute->allow_multi_select
+                        ? $definitionValues->all()
+                        : $definitionValues->first(),
+                ];
+            });
 
         $eventDateIds = $this->selectedEventDates()
             ->pluck('id')
diff --git a/app/Domains/Catalog/Requests/StoreCatalogItemRequest.php b/app/Domains/Catalog/Requests/StoreCatalogItemRequest.php
index 222292c..e5d9cfc 100644
--- a/app/Domains/Catalog/Requests/StoreCatalogItemRequest.php
+++ b/app/Domains/Catalog/Requests/StoreCatalogItemRequest.php
@@ -109,7 +109,8 @@ class StoreCatalogItemRequest extends FormRequest
             'variants.*.reserved_stock' => ['prohibited'],
             'variants.*.sold_units' => ['prohibited'],
             'variants.*.values' => ['sometimes', 'array'],
-            'variants.*.values.*' => ['nullable', 'string'],
+            'variants.*.values.*' => ['nullable'],
+            'variants.*.values.*.*' => ['required', 'string'],
             'variants.*.images' => ['sometimes', 'array'],
             'variants.*.images.*' => ['required', new ImageOrBase64Rule],
             'components' => [
diff --git a/app/Domains/Catalog/Services/CatalogService.php b/app/Domains/Catalog/Services/CatalogService.php
index 8fcc7ea..6e7b137 100644
--- a/app/Domains/Catalog/Services/CatalogService.php
+++ b/app/Domains/Catalog/Services/CatalogService.php
@@ -569,10 +569,16 @@ class CatalogService
                 ]);
             }
 
-            $variant->definitions()->create([
-                'item_attribute_id' => $itemAttribute->id,
-                'value' => $value,
-            ]);
+            foreach ($this->validatedVariantValues(
+                $itemAttribute,
+                $value,
+                "variants.{$index}.values.{$attributeCode}",
+            ) as $validatedValue) {
+                $variant->definitions()->create([
+                    'item_attribute_id' => $itemAttribute->id,
+                    'value' => $validatedValue,
+                ]);
+            }
         }
 
         return $variant;
@@ -618,8 +624,14 @@ class CatalogService
             $combination = [$eventDateIds];
 
             foreach ($attributeCodes as $attributeCode) {
-                $value = trim((string) ($variant['values'][$attributeCode] ?? ''));
-                $combination[] = Str::ascii(mb_strtolower($value));
+                $values = $variant['values'][$attributeCode] ?? '';
+                $normalizedValues = collect(is_array($values) ? $values : [$values])
+                    ->map(fn ($value): string => $this->normalizeVariantValue((string) $value))
+                    ->unique()
+                    ->sort()
+                    ->values()
+                    ->implode(',');
+                $combination[] = $normalizedValues;
             }
 
             $key = implode('|', $combination);
@@ -633,6 +645,72 @@ class CatalogService
         }
     }
 
+    /** @return array<int, string> */
+    private function validatedVariantValues(
+        ItemAttribute $itemAttribute,
+        mixed $value,
+        string $validationKey,
+    ): array {
+        $values = is_array($value) ? array_values($value) : [$value];
+
+        if ($values === [] || (! $itemAttribute->allow_multi_select && count($values) !== 1)) {
+            throw ValidationException::withMessages([
+                $validationKey => [
+                    $itemAttribute->allow_multi_select
+                        ? 'At least one value must be selected.'
+                        : 'Exactly one value must be selected.',
+                ],
+            ]);
+        }
+
+        if (collect($values)->contains(fn ($item): bool => ! is_string($item) || trim($item) === '')) {
+            throw ValidationException::withMessages([
+                $validationKey => ['Every selected value must be a non-empty string.'],
+            ]);
+        }
+
+        $normalizedValues = collect($values)
+            ->map(fn (string $item): string => $this->normalizeVariantValue($item));
+
+        if ($normalizedValues->unique()->count() !== count($values)) {
+            throw ValidationException::withMessages([
+                $validationKey => ['Selected values must be distinct.'],
+            ]);
+        }
+
+        $attribute = $itemAttribute->attribute;
+        if ($attribute->type->supportsOptions() && ! $attribute->type->usesDynamicOptions()) {
+            $optionsByNormalizedValue = $attribute->options
+                ->keyBy(fn ($option): string => $this->normalizeVariantValue($option->value));
+
+            $resolvedOptions = $normalizedValues->map(fn (string $normalizedValue) => $optionsByNormalizedValue->get($normalizedValue));
+            if ($resolvedOptions->contains(null)) {
+                throw ValidationException::withMessages([
+                    $validationKey => ['One or more selected values are not valid attribute options.'],
+                ]);
+            }
+
+            $validityTimeIds = $resolvedOptions
+                ->pluck('validity_time_id')
+                ->filter()
+                ->unique();
+            if ($validityTimeIds->count() > 1) {
+                throw ValidationException::withMessages([
+                    $validationKey => ['Selected values cannot have different validity windows.'],
+                ]);
+            }
+
+            return $resolvedOptions->pluck('value')->all();
+        }
+
+        return collect($values)->map(fn (string $item): string => trim($item))->all();
+    }
+
+    private function normalizeVariantValue(string $value): string
+    {
+        return Str::ascii(mb_strtolower(trim($value)));
+    }
+
     /**
      * @param  array<string, mixed>  $data
      * @param  array<int, array<string, mixed>>  $variants
diff --git a/app/Domains/Purchase/Resources/PurchaseItemResource.php b/app/Domains/Purchase/Resources/PurchaseItemResource.php
index aca7d9d..06938ab 100644
--- a/app/Domains/Purchase/Resources/PurchaseItemResource.php
+++ b/app/Domains/Purchase/Resources/PurchaseItemResource.php
@@ -99,10 +99,18 @@ class PurchaseItemResource extends JsonResource
         }
 
         $attributes = $variant->definitions
-            ->map(fn ($definition): array => [
-                'name' => (string) ($definition->itemAttribute?->attribute?->nombre ?? ''),
-                'value' => $definition->value,
-            ])
+            ->groupBy('item_attribute_id')
+            ->map(function ($definitions): array {
+                $itemAttribute = $definitions->first()?->itemAttribute;
+                $values = $definitions->pluck('value')->values();
+
+                return [
+                    'name' => (string) ($itemAttribute?->attribute?->nombre ?? ''),
+                    'value' => $itemAttribute?->allow_multi_select
+                        ? $values->all()
+                        : $values->first(),
+                ];
+            })
             ->filter(fn (array $attribute): bool => $attribute['name'] !== '' || $attribute['value'] !== null)
             ->values();
 
diff --git a/app/Domains/Purchase/Services/Checkout/PurchaseItemSnapshotFactory.php b/app/Domains/Purchase/Services/Checkout/PurchaseItemSnapshotFactory.php
index f0974cf..fbfbcff 100644
--- a/app/Domains/Purchase/Services/Checkout/PurchaseItemSnapshotFactory.php
+++ b/app/Domains/Purchase/Services/Checkout/PurchaseItemSnapshotFactory.php
@@ -54,10 +54,18 @@ class PurchaseItemSnapshotFactory
     private function snapshotAttributes(Variant $variant): array
     {
         $attributes = $variant->definitions
-            ->map(fn ($definition): array => [
-                'name' => (string) ($definition->itemAttribute?->attribute?->nombre ?? ''),
-                'value' => $definition->value,
-            ])
+            ->groupBy('item_attribute_id')
+            ->map(function ($definitions): array {
+                $itemAttribute = $definitions->first()?->itemAttribute;
+                $values = $definitions->pluck('value')->values();
+
+                return [
+                    'name' => (string) ($itemAttribute?->attribute?->nombre ?? ''),
+                    'value' => $itemAttribute?->allow_multi_select
+                        ? $values->all()
+                        : $values->first(),
+                ];
+            })
             ->filter(fn (array $attribute): bool => $attribute['name'] !== '' || $attribute['value'] !== null)
             ->values();
 
diff --git a/tests/Feature/Catalog/CatalogServiceTest.php b/tests/Feature/Catalog/CatalogServiceTest.php
index 6e79f22..e671c98 100644
--- a/tests/Feature/Catalog/CatalogServiceTest.php
+++ b/tests/Feature/Catalog/CatalogServiceTest.php
@@ -172,6 +172,32 @@ class CatalogServiceTest extends TestCase
         );
     }
 
+    public function test_it_creates_multiple_values_for_any_multi_select_attribute(): void
+    {
+        $color = $this->createAttribute('color', FieldType::Select);
+        $color->options()->createMany([
+            ['value' => 'Green', 'label' => 'Green', 'sort_order' => 1],
+            ['value' => 'White', 'label' => 'White', 'sort_order' => 2],
+        ]);
+
+        $item = $this->service->create([
+            'tenant_code' => $this->tenant->codigo,
+            'slug' => 'multi-color-shirt',
+            'nombre' => 'Multi-color shirt',
+            'precio' => 100,
+            'attribute_codes' => ['color'],
+            'multi_select_attribute_codes' => ['color'],
+            'variants' => [[
+                'real_stock' => 5,
+                'values' => ['color' => ['White', 'Green']],
+            ]],
+        ]);
+
+        $variant = $item->variants->sole();
+        $this->assertSame(['White', 'Green'], $variant->definitions->pluck('value')->all());
+        $this->assertSame(['White', 'Green'], $variant->selectionValues()->get('color'));
+    }
+
     public function test_it_rejects_duplicate_variant_combinations(): void
     {
         $sector = $this->createAttribute('sector');