diff --git a/backend/src/server/routes/v1/integration-auth-router.ts b/backend/src/server/routes/v1/integration-auth-router.ts
index ffeb748b8..185738de6 100644
--- a/backend/src/server/routes/v1/integration-auth-router.ts
+++ b/backend/src/server/routes/v1/integration-auth-router.ts
@@ -1151,6 +1151,50 @@ export const registerIntegrationAuthRouter = async (server: FastifyZodProvider)
     }
   });
 
+  server.route({
+    method: "GET",
+    url: "/:integrationAuthId/vercel/custom-environments",
+    config: {
+      rateLimit: readLimit
+    },
+    onRequest: verifyAuth([AuthMode.JWT]),
+    schema: {
+      querystring: z.object({
+        teamId: z.string().trim()
+      }),
+      params: z.object({
+        integrationAuthId: z.string().trim()
+      }),
+      response: {
+        200: z.object({
+          environments: z
+            .object({
+              appId: z.string(),
+              customEnvironments: z
+                .object({
+                  id: z.string(),
+                  slug: z.string()
+                })
+                .array()
+            })
+            .array()
+        })
+      }
+    },
+    handler: async (req) => {
+      const environments = await server.services.integrationAuth.getVercelCustomEnvironments({
+        actorId: req.permission.id,
+        actor: req.permission.type,
+        actorAuthMethod: req.permission.authMethod,
+        actorOrgId: req.permission.orgId,
+        id: req.params.integrationAuthId,
+        teamId: req.query.teamId
+      });
+
+      return { environments };
+    }
+  });
+
   server.route({
     method: "GET",
     url: "/:integrationAuthId/octopus-deploy/spaces",
diff --git a/backend/src/services/integration-auth/integration-app-list.ts b/backend/src/services/integration-auth/integration-app-list.ts
index 3b8078cc1..126037895 100644
--- a/backend/src/services/integration-auth/integration-app-list.ts
+++ b/backend/src/services/integration-auth/integration-app-list.ts
@@ -132,16 +132,26 @@ const getAppsHeroku = async ({ accessToken }: { accessToken: string }) => {
 
 /**
  * Return list of names of apps for Vercel integration
+ * This is re-used for getting custom environments for Vercel
  */
-const getAppsVercel = async ({ accessToken, teamId }: { teamId?: string | null; accessToken: string }) => {
-  const apps: Array<{ name: string; appId: string }> = [];
+export const getAppsVercel = async ({ accessToken, teamId }: { teamId?: string | null; accessToken: string }) => {
+  const apps: Array<{ name: string; appId: string; customEnvironments: Array<{ slug: string; id: string }> }> = [];
 
   const limit = "20";
   let hasMorePages = true;
   let next: number | null = null;
 
   interface Response {
-    projects: { name: string; id: string }[];
+    projects: {
+      name: string;
+      id: string;
+      customEnvironments?: {
+        id: string;
+        type: string;
+        description: string;
+        slug: string;
+      }[];
+    }[];
     pagination: {
       count: number;
       next: number | null;
@@ -173,7 +183,12 @@ const getAppsVercel = async ({ accessToken, teamId }: { teamId?: string | null;
     data.projects.forEach((a) => {
       apps.push({
         name: a.name,
-        appId: a.id
+        appId: a.id,
+        customEnvironments:
+          a.customEnvironments?.map((env) => ({
+            slug: env.slug,
+            id: env.id
+          })) ?? []
       });
     });
 
diff --git a/backend/src/services/integration-auth/integration-auth-service.ts b/backend/src/services/integration-auth/integration-auth-service.ts
index d96643a19..61f753348 100644
--- a/backend/src/services/integration-auth/integration-auth-service.ts
+++ b/backend/src/services/integration-auth/integration-auth-service.ts
@@ -25,11 +25,12 @@ import { TIntegrationDALFactory } from "../integration/integration-dal";
 import { TKmsServiceFactory } from "../kms/kms-service";
 import { KmsDataKey } from "../kms/kms-types";
 import { TProjectBotServiceFactory } from "../project-bot/project-bot-service";
-import { getApps } from "./integration-app-list";
+import { getApps, getAppsVercel } from "./integration-app-list";
 import { TCircleCIContext } from "./integration-app-types";
 import { TIntegrationAuthDALFactory } from "./integration-auth-dal";
 import { IntegrationAuthMetadataSchema, TIntegrationAuthMetadata } from "./integration-auth-schema";
 import {
+  GetVercelCustomEnvironmentsDTO,
   OctopusDeployScope,
   TBitbucketEnvironment,
   TBitbucketWorkspace,
@@ -1825,6 +1826,41 @@ export const integrationAuthServiceFactory = ({
     return integrationAuthDAL.create(newIntegrationAuth);
   };
 
+  const getVercelCustomEnvironments = async ({
+    actorId,
+    actor,
+    actorOrgId,
+    actorAuthMethod,
+    teamId,
+    id
+  }: GetVercelCustomEnvironmentsDTO) => {
+    const integrationAuth = await integrationAuthDAL.findById(id);
+    if (!integrationAuth) throw new NotFoundError({ message: `Integration auth with ID '${id}' not found` });
+
+    const { permission } = await permissionService.getProjectPermission({
+      actor,
+      actorId,
+      projectId: integrationAuth.projectId,
+      actorAuthMethod,
+      actorOrgId,
+      actionProjectType: ActionProjectType.SecretManager
+    });
+    ForbiddenError.from(permission).throwUnlessCan(ProjectPermissionActions.Read, ProjectPermissionSub.Integrations);
+
+    const { botKey, shouldUseSecretV2Bridge } = await projectBotService.getBotKey(integrationAuth.projectId);
+    const { accessToken } = await getIntegrationAccessToken(integrationAuth, shouldUseSecretV2Bridge, botKey);
+
+    const vercelApps = await getAppsVercel({
+      accessToken,
+      teamId
+    });
+
+    return vercelApps.map((app) => ({
+      customEnvironments: app.customEnvironments,
+      appId: app.appId
+    }));
+  };
+
   const getOctopusDeploySpaces = async ({
     actorId,
     actor,
@@ -1944,6 +1980,7 @@ export const integrationAuthServiceFactory = ({
     getIntegrationAccessToken,
     duplicateIntegrationAuth,
     getOctopusDeploySpaces,
-    getOctopusDeployScopeValues
+    getOctopusDeployScopeValues,
+    getVercelCustomEnvironments
   };
 };
diff --git a/backend/src/services/integration-auth/integration-auth-types.ts b/backend/src/services/integration-auth/integration-auth-types.ts
index 68d7bf5b9..8efe6b851 100644
--- a/backend/src/services/integration-auth/integration-auth-types.ts
+++ b/backend/src/services/integration-auth/integration-auth-types.ts
@@ -284,3 +284,8 @@ export type TOctopusDeployVariableSet = {
     Self: string;
   };
 };
+
+export type GetVercelCustomEnvironmentsDTO = {
+  teamId: string;
+  id: string;
+} & Omit<TProjectPermission, "projectId">;
diff --git a/backend/src/services/integration-auth/integration-sync-secret.ts b/backend/src/services/integration-auth/integration-sync-secret.ts
index 96e8ec598..249307f8d 100644
--- a/backend/src/services/integration-auth/integration-sync-secret.ts
+++ b/backend/src/services/integration-auth/integration-sync-secret.ts
@@ -1450,9 +1450,13 @@ const syncSecretsVercel = async ({
   secrets: Record<string, { value: string; comment?: string } | null>;
   accessToken: string;
 }) => {
+  const isCustomEnvironment = !["development", "preview", "production"].includes(
+    integration.targetEnvironment as string
+  );
   interface VercelSecret {
     id?: string;
     type: string;
+    customEnvironmentIds?: string[];
     key: string;
     value: string;
     target: string[];
@@ -1486,6 +1490,16 @@ const syncSecretsVercel = async ({
       }
     )
   ).data.envs.filter((secret) => {
+    if (isCustomEnvironment) {
+      if (!secret.customEnvironmentIds?.includes(integration.targetEnvironment as string)) {
+        // case: secret does not have the same custom environment
+        return false;
+      }
+
+      // no need to check for preview environment, as custom environments are not available in preview
+      return true;
+    }
+
     if (!secret.target.includes(integration.targetEnvironment as string)) {
       // case: secret does not have the same target environment
       return false;
@@ -1583,7 +1597,13 @@ const syncSecretsVercel = async ({
             key,
             value: infisicalSecrets[key]?.value,
             type: "encrypted",
-            target: [integration.targetEnvironment as string],
+            ...(isCustomEnvironment
+              ? {
+                  customEnvironmentIds: [integration.targetEnvironment as string]
+                }
+              : {
+                  target: [integration.targetEnvironment as string]
+                }),
             ...(integration.path
               ? {
                   gitBranch: integration.path
@@ -1607,9 +1627,19 @@ const syncSecretsVercel = async ({
             key,
             value: infisicalSecrets[key]?.value,
             type: res[key].type,
-            target: res[key].target.includes(integration.targetEnvironment as string)
-              ? [...res[key].target]
-              : [...res[key].target, integration.targetEnvironment as string],
+
+            ...(!isCustomEnvironment
+              ? {
+                  target: res[key].target.includes(integration.targetEnvironment as string)
+                    ? [...res[key].target]
+                    : [...res[key].target, integration.targetEnvironment as string]
+                }
+              : {
+                  customEnvironmentIds: res[key].customEnvironmentIds?.includes(integration.targetEnvironment as string)
+                    ? [...(res[key].customEnvironmentIds || [])]
+                    : [...(res[key]?.customEnvironmentIds || []), integration.targetEnvironment as string]
+                }),
+
             ...(integration.path
               ? {
                   gitBranch: integration.path
diff --git a/frontend/src/hooks/api/integrationAuth/index.tsx b/frontend/src/hooks/api/integrationAuth/index.tsx
index e7ee5928a..eab946ba6 100644
--- a/frontend/src/hooks/api/integrationAuth/index.tsx
+++ b/frontend/src/hooks/api/integrationAuth/index.tsx
@@ -16,5 +16,6 @@ export {
   useGetIntegrationAuthTeamCityBuildConfigs,
   useGetIntegrationAuthTeams,
   useGetIntegrationAuthVercelBranches,
+  useGetIntegrationAuthVercelCustomEnvironments,
   useSaveIntegrationAccessToken
 } from "./queries";
diff --git a/frontend/src/hooks/api/integrationAuth/queries.tsx b/frontend/src/hooks/api/integrationAuth/queries.tsx
index 44b199a24..f62887043 100644
--- a/frontend/src/hooks/api/integrationAuth/queries.tsx
+++ b/frontend/src/hooks/api/integrationAuth/queries.tsx
@@ -21,7 +21,8 @@ import {
   Team,
   TeamCityBuildConfig,
   TGetIntegrationAuthOctopusDeployScopeValuesDTO,
-  TOctopusDeployVariableSetScopeValues
+  TOctopusDeployVariableSetScopeValues,
+  VercelEnvironment
 } from "./types";
 
 const integrationAuthKeys = {
@@ -132,7 +133,9 @@ const integrationAuthKeys = {
   }: TGetIntegrationAuthOctopusDeployScopeValuesDTO) =>
     [{ integrationAuthId }, "getIntegrationAuthOctopusDeployScopeValues", params] as const,
   getIntegrationAuthCircleCIOrganizations: (integrationAuthId: string) =>
-    [{ integrationAuthId }, "getIntegrationAuthCircleCIOrganizations"] as const
+    [{ integrationAuthId }, "getIntegrationAuthCircleCIOrganizations"] as const,
+  getIntegrationAuthVercelCustomEnv: (integrationAuthId: string, teamId: string) =>
+    [{ integrationAuthId, teamId }, "integrationAuthVercelCustomEnv"] as const
 };
 
 const fetchIntegrationAuthById = async (integrationAuthId: string) => {
@@ -362,6 +365,29 @@ const fetchIntegrationAuthQoveryScopes = async ({
   return undefined;
 };
 
+const fetchIntegrationAuthVercelCustomEnvironments = async ({
+  integrationAuthId,
+  teamId
+}: {
+  integrationAuthId: string;
+  teamId: string;
+}) => {
+  const {
+    data: { environments }
+  } = await apiRequest.get<{
+    environments: {
+      appId: string;
+      customEnvironments: VercelEnvironment[];
+    }[];
+  }>(`/api/v1/integration-auth/${integrationAuthId}/vercel/custom-environments`, {
+    params: {
+      teamId
+    }
+  });
+
+  return environments;
+};
+
 const fetchIntegrationAuthHerokuPipelines = async ({
   integrationAuthId
 }: {
@@ -730,6 +756,24 @@ export const useGetIntegrationAuthQoveryScopes = ({
   });
 };
 
+export const useGetIntegrationAuthVercelCustomEnvironments = ({
+  integrationAuthId,
+  teamId
+}: {
+  integrationAuthId: string;
+  teamId: string;
+}) => {
+  return useQuery({
+    queryKey: integrationAuthKeys.getIntegrationAuthVercelCustomEnv(integrationAuthId, teamId),
+    queryFn: () =>
+      fetchIntegrationAuthVercelCustomEnvironments({
+        integrationAuthId,
+        teamId
+      }),
+    enabled: Boolean(teamId && integrationAuthId)
+  });
+};
+
 export const useGetIntegrationAuthHerokuPipelines = ({
   integrationAuthId
 }: {
diff --git a/frontend/src/hooks/api/integrationAuth/types.ts b/frontend/src/hooks/api/integrationAuth/types.ts
index e2dee6067..b57e5aeca 100644
--- a/frontend/src/hooks/api/integrationAuth/types.ts
+++ b/frontend/src/hooks/api/integrationAuth/types.ts
@@ -43,6 +43,11 @@ export type Environment = {
   environmentId: string;
 };
 
+export type VercelEnvironment = {
+  id: string;
+  slug: string;
+};
+
 export type ChecklyGroup = {
   name: string;
   groupId: number;
diff --git a/frontend/src/pages/secret-manager/integrations/VercelConfigurePage/VercelConfigurePage.tsx b/frontend/src/pages/secret-manager/integrations/VercelConfigurePage/VercelConfigurePage.tsx
index a113dba15..fabccb6bb 100644
--- a/frontend/src/pages/secret-manager/integrations/VercelConfigurePage/VercelConfigurePage.tsx
+++ b/frontend/src/pages/secret-manager/integrations/VercelConfigurePage/VercelConfigurePage.tsx
@@ -1,4 +1,4 @@
-import { useEffect, useState } from "react";
+import { useEffect, useMemo, useState } from "react";
 import { Helmet } from "react-helmet";
 import {
   faArrowUpRightFromSquare,
@@ -25,7 +25,8 @@ import { useCreateIntegration } from "@app/hooks/api";
 import {
   useGetIntegrationAuthApps,
   useGetIntegrationAuthById,
-  useGetIntegrationAuthVercelBranches
+  useGetIntegrationAuthVercelBranches,
+  useGetIntegrationAuthVercelCustomEnvironments
 } from "@app/hooks/api/integrationAuth";
 import { IntegrationSyncBehavior } from "@app/hooks/api/integrations/types";
 
@@ -75,6 +76,11 @@ export const VercelConfigurePage = () => {
       teamId: integrationAuth?.teamId as string
     });
 
+  const { data: customEnvironments } = useGetIntegrationAuthVercelCustomEnvironments({
+    teamId: integrationAuth?.teamId as string,
+    integrationAuthId: integrationAuthId as string
+  });
+
   const { data: branches } = useGetIntegrationAuthVercelBranches({
     integrationAuthId: integrationAuthId as string,
     appId: targetAppId
@@ -135,6 +141,26 @@ export const VercelConfigurePage = () => {
     }
   };
 
+  const selectedVercelEnvironments = useMemo(() => {
+    let selectedEnvironments = vercelEnvironments;
+
+    const environments = customEnvironments?.find(
+      (e) => e.appId === targetAppId
+    )?.customEnvironments;
+
+    if (environments && environments.length > 0) {
+      selectedEnvironments = [
+        ...selectedEnvironments,
+        ...environments.map((env) => ({
+          name: env.slug,
+          slug: env.id
+        }))
+      ];
+    }
+
+    return selectedEnvironments;
+  }, [targetAppId, customEnvironments]);
+
   return integrationAuth &&
     selectedSourceEnvironment &&
     integrationAuthApps &&
@@ -210,7 +236,13 @@ export const VercelConfigurePage = () => {
         >
           <Select
             value={targetAppId}
-            onValueChange={(val) => setTargetAppId(val)}
+            onValueChange={(val) => {
+              if (vercelEnvironments.every((env) => env.slug !== targetEnvironment)) {
+                setTargetEnvironment(vercelEnvironments[0].slug);
+              }
+
+              setTargetAppId(val);
+            }}
             className="w-full border border-mineshaft-500"
             isDisabled={integrationAuthApps.length === 0}
           >
@@ -236,7 +268,7 @@ export const VercelConfigurePage = () => {
             onValueChange={(val) => setTargetEnvironment(val)}
             className="w-full border border-mineshaft-500"
           >
-            {vercelEnvironments.map((vercelEnvironment) => (
+            {selectedVercelEnvironments.map((vercelEnvironment) => (
               <SelectItem
                 value={vercelEnvironment.slug}
                 key={`target-environment-${vercelEnvironment.slug}`}