diff --git a/packages/twenty-front/src/modules/settings/data-model/fields/forms/select/components/SettingsDataModelFieldSelectForm.tsx b/packages/twenty-front/src/modules/settings/data-model/fields/forms/select/components/SettingsDataModelFieldSelectForm.tsx
index 69a4e43499..64f8afeb67 100644
--- a/packages/twenty-front/src/modules/settings/data-model/fields/forms/select/components/SettingsDataModelFieldSelectForm.tsx
+++ b/packages/twenty-front/src/modules/settings/data-model/fields/forms/select/components/SettingsDataModelFieldSelectForm.tsx
@@ -17,6 +17,7 @@ import { moveArrayItem } from '~/utils/array/moveArrayItem';
 import { toSpliced } from '~/utils/array/toSpliced';
 import { applySimpleQuotesToString } from '~/utils/string/applySimpleQuotesToString';
 
+import { useFieldMetadataItemById } from '@/object-metadata/hooks/useFieldMetadataItemById';
 import { AdvancedSettingsWrapper } from '@/settings/components/AdvancedSettingsWrapper';
 import { isAdvancedModeEnabledState } from '@/ui/navigation/navigation-drawer/states/isAdvancedModeEnabledState';
 import { useTheme } from '@emotion/react';
@@ -119,6 +120,10 @@ export const SettingsDataModelFieldSelectForm = ({
     useSelectSettingsFormInitialValues({
       fieldMetadataId: existingFieldMetadataId,
     });
+  const { fieldMetadataItem } = useFieldMetadataItemById(
+    existingFieldMetadataId,
+  );
+  const isNullable = fieldMetadataItem?.isNullable;
 
   const isAdvancedModeEnabled = useRecoilValue(isAdvancedModeEnabledState);
 
@@ -340,6 +345,7 @@ export const SettingsDataModelFieldSelectForm = ({
                               onChange(nextOptions);
                             }}
                             isDefault={isOptionDefaultValue(option.value)}
+                            fieldIsNullable={!!isNullable}
                             onSetAsDefault={() => {
                               if (disabled) {
                                 return;
diff --git a/packages/twenty-front/src/modules/settings/data-model/fields/forms/select/components/SettingsDataModelFieldSelectFormOptionRow.tsx b/packages/twenty-front/src/modules/settings/data-model/fields/forms/select/components/SettingsDataModelFieldSelectFormOptionRow.tsx
index 8ca14e602a..e43b0b8337 100644
--- a/packages/twenty-front/src/modules/settings/data-model/fields/forms/select/components/SettingsDataModelFieldSelectFormOptionRow.tsx
+++ b/packages/twenty-front/src/modules/settings/data-model/fields/forms/select/components/SettingsDataModelFieldSelectFormOptionRow.tsx
@@ -32,6 +32,7 @@ type SettingsDataModelFieldSelectFormOptionRowProps = {
   onInputEnter?: () => void;
   option: FieldMetadataItemOption;
   isNewRow?: boolean;
+  fieldIsNullable?: boolean;
 };
 
 const StyledRow = styled.div`
@@ -76,6 +77,7 @@ export const SettingsDataModelFieldSelectFormOptionRow = ({
   onInputEnter,
   option,
   isNewRow,
+  fieldIsNullable,
 }: SettingsDataModelFieldSelectFormOptionRowProps) => {
   const theme = useTheme();
   const SELECT_COLOR_DROPDOWN_ID = `select-color-dropdown-${option.id}`;
@@ -84,6 +86,8 @@ export const SettingsDataModelFieldSelectFormOptionRow = ({
   const { closeDropdown: closeColorDropdown } = useCloseDropdown();
   const { closeDropdown: closeActionsDropdown } = useCloseDropdown();
 
+  const shouldForbidRemoveAsDefault = isDefault && !fieldIsNullable;
+
   const handleInputEnter = () => {
     onInputEnter?.();
   };
@@ -157,43 +161,49 @@ export const SettingsDataModelFieldSelectFormOptionRow = ({
         dropdownId={SELECT_ACTIONS_DROPDOWN_ID}
         dropdownPlacement="right-start"
         clickableComponent={
-          <StyledLightIconButton accent="tertiary" Icon={IconDotsVertical} />
+          <StyledLightIconButton
+            accent="tertiary"
+            Icon={IconDotsVertical}
+            disabled={shouldForbidRemoveAsDefault}
+          />
         }
         dropdownComponents={
-          <DropdownContent>
-            <DropdownMenuItemsContainer>
-              {isDefault ? (
-                <MenuItem
-                  LeftIcon={IconX}
-                  text={t`Remove as default`}
-                  onClick={() => {
-                    onRemoveAsDefault?.();
-                    closeActionsDropdown(SELECT_ACTIONS_DROPDOWN_ID);
-                  }}
-                />
-              ) : (
-                <MenuItem
-                  LeftIcon={IconCheck}
-                  text={t`Set as default`}
-                  onClick={() => {
-                    onSetAsDefault?.();
-                    closeActionsDropdown(SELECT_ACTIONS_DROPDOWN_ID);
-                  }}
-                />
-              )}
-              {!!onRemove && !isDefault && (
-                <MenuItem
-                  accent="danger"
-                  LeftIcon={IconTrash}
-                  text={t`Remove option`}
-                  onClick={() => {
-                    onRemove();
-                    closeActionsDropdown(SELECT_ACTIONS_DROPDOWN_ID);
-                  }}
-                />
-              )}
-            </DropdownMenuItemsContainer>
-          </DropdownContent>
+          shouldForbidRemoveAsDefault ? null : (
+            <DropdownContent>
+              <DropdownMenuItemsContainer>
+                {isDefault ? (
+                  <MenuItem
+                    LeftIcon={IconX}
+                    text={t`Remove as default`}
+                    onClick={() => {
+                      onRemoveAsDefault?.();
+                      closeActionsDropdown(SELECT_ACTIONS_DROPDOWN_ID);
+                    }}
+                  />
+                ) : (
+                  <MenuItem
+                    LeftIcon={IconCheck}
+                    text={t`Set as default`}
+                    onClick={() => {
+                      onSetAsDefault?.();
+                      closeActionsDropdown(SELECT_ACTIONS_DROPDOWN_ID);
+                    }}
+                  />
+                )}
+                {!!onRemove && !isDefault && (
+                  <MenuItem
+                    accent="danger"
+                    LeftIcon={IconTrash}
+                    text={t`Remove option`}
+                    onClick={() => {
+                      onRemove();
+                      closeActionsDropdown(SELECT_ACTIONS_DROPDOWN_ID);
+                    }}
+                  />
+                )}
+              </DropdownMenuItemsContainer>
+            </DropdownContent>
+          )
         }
       />
     </StyledRow>
diff --git a/packages/twenty-server/src/engine/workspace-manager/workspace-migration-v2/workspace-migration-builder-v2/validators/services/flat-field-metadata-validator.service.ts b/packages/twenty-server/src/engine/workspace-manager/workspace-migration-v2/workspace-migration-builder-v2/validators/services/flat-field-metadata-validator.service.ts
index 6023ca3d9b..66bae5fffa 100644
--- a/packages/twenty-server/src/engine/workspace-manager/workspace-migration-v2/workspace-migration-builder-v2/validators/services/flat-field-metadata-validator.service.ts
+++ b/packages/twenty-server/src/engine/workspace-manager/workspace-migration-v2/workspace-migration-builder-v2/validators/services/flat-field-metadata-validator.service.ts
@@ -158,6 +158,17 @@ export class FlatFieldMetadataValidatorService {
       });
     }
 
+    if (
+      flatFieldMetadataToValidate.isNullable === false &&
+      flatFieldMetadataToValidate.defaultValue === null
+    ) {
+      validationResult.errors.push({
+        code: FieldMetadataExceptionCode.INVALID_FIELD_INPUT,
+        message: 'Default value cannot be null for non-nullable fields',
+        userFriendlyMessage: msg`Default value cannot be null.`,
+      });
+    }
+
     const fieldMetadataTypeValidationErrors =
       this.flatFieldMetadataTypeValidatorService.validateFlatFieldMetadataTypeSpecificities(
         {