diff --git a/src/Fieldtypes/HasSelectOptions.php b/src/Fieldtypes/HasSelectOptions.php
index 219a664e0c8..0f04e6a38d7 100644
--- a/src/Fieldtypes/HasSelectOptions.php
+++ b/src/Fieldtypes/HasSelectOptions.php
@@ -66,9 +66,18 @@ public function preProcess($value)
             return [];
         }
 
+        $keys = collect($this->getOptions())->pluck('value');
+
         // NOTE: Null-coalescing into `[null]` as that matches old behaviour.
-        $values = collect($value ?? [null])->map(function ($value) {
-            return $this->config('cast_booleans') ? $this->castFromBoolean($value) : $value;
+        $values = collect($value ?? [null])->map(function ($value) use ($keys) {
+            $value = $this->config('cast_booleans') ? $this->castFromBoolean($value) : $value;
+
+            // Front-end form submissions store numeric keys as strings, e.g. '1' for an option key of 1.
+            if (is_string($value) && ! $keys->containsStrict($value)) {
+                $value = $keys->first(fn ($key) => is_int($key) && (string) $key === $value) ?? $value;
+            }
+
+            return $value;
         });
 
         return $multiple ? $values->all() : $values->first();
diff --git a/tests/Fieldtypes/HasSelectOptionsTests.php b/tests/Fieldtypes/HasSelectOptionsTests.php
index fa655bf5482..efe3f899dd4 100644
--- a/tests/Fieldtypes/HasSelectOptionsTests.php
+++ b/tests/Fieldtypes/HasSelectOptionsTests.php
@@ -104,6 +104,29 @@ public static function preProcessIndexProvider()
                 'two',
                 ['two'],
             ],
+            'numeric keys with string value' => [
+                [
+                    ['key' => 926450000, 'value' => 'One'],
+                    ['key' => 926450001, 'value' => 'Two'],
+                ],
+                '926450001',
+                ['Two'],
+            ],
+            'numeric keys with differently formatted string value' => [
+                [
+                    ['key' => 1, 'value' => 'One'],
+                ],
+                '01',
+                ['01'],
+            ],
+            'numeric and string keys with string value' => [
+                [
+                    ['key' => 1, 'value' => 'One'],
+                    ['key' => '1', 'value' => 'String One'],
+                ],
+                '1',
+                ['String One'],
+            ],
         ];
     }
 }