diff --git a/jupyter_server/services/sessions/handlers.py b/jupyter_server/services/sessions/handlers.py
index 3e013c0335..7aec4a6159 100644
--- a/jupyter_server/services/sessions/handlers.py
+++ b/jupyter_server/services/sessions/handlers.py
@@ -77,6 +77,7 @@ async def post(self):
         kernel = model.get("kernel", {})
         kernel_name = kernel.get("name", None)
         kernel_id = kernel.get("id", None)
+        custom_kernel_specs = kernel.get("custom_kernel_specs", {})
 
         if not kernel_id and not kernel_name:
             self.log.debug("No kernel specified, using default kernel")
@@ -93,6 +94,7 @@ async def post(self):
                     kernel_id=kernel_id,
                     name=name,
                     type=mtype,
+                    custom_kernel_specs=custom_kernel_specs
                 )
             except NoSuchKernel:
                 msg = (
@@ -152,6 +154,9 @@ async def patch(self, session_id):
             changes["name"] = model["name"]
         if "type" in model:
             changes["type"] = model["type"]
+        if "custom_kernel_specs" in model:
+            changes["custom_kernel_specs"] = model["custom_kernel_specs"]
+        
         if "kernel" in model:
             # Kernel id takes precedence over name.
             if model["kernel"].get("id") is not None:
@@ -160,6 +165,10 @@ async def patch(self, session_id):
                     raise web.HTTPError(400, "No such kernel: %s" % kernel_id)
                 changes["kernel_id"] = kernel_id
             elif model["kernel"].get("name") is not None:
+                if "custom_kernel_specs" in model["kernel"]:
+                    custom_kernel_specs = model["kernel"]["custom_kernel_specs"]
+                else:
+                    custom_kernel_specs = None
                 kernel_name = model["kernel"]["name"]
                 kernel_id = await sm.start_kernel_for_session(
                     session_id,
@@ -167,6 +176,7 @@ async def patch(self, session_id):
                     name=before["name"],
                     path=before["path"],
                     type=before["type"],
+                    custom_kernel_specs = custom_kernel_specs
                 )
                 changes["kernel_id"] = kernel_id
 
diff --git a/jupyter_server/services/sessions/sessionmanager.py b/jupyter_server/services/sessions/sessionmanager.py
index 5f3a19c71d..db58fe57a8 100644
--- a/jupyter_server/services/sessions/sessionmanager.py
+++ b/jupyter_server/services/sessions/sessionmanager.py
@@ -267,6 +267,7 @@ async def create_session(
         type: Optional[str] = None,
         kernel_name: Optional[KernelName] = None,
         kernel_id: Optional[str] = None,
+        custom_kernel_specs: Optional[Dict[str, Any]] = None
     ) -> Dict[str, Any]:
         """Creates a session and returns its model
 
@@ -282,8 +283,9 @@ async def create_session(
         if kernel_id is not None and kernel_id in self.kernel_manager:
             pass
         else:
+            #
             kernel_id = await self.start_kernel_for_session(
-                session_id, path, name, type, kernel_name
+                session_id, path, name, type, kernel_name, custom_kernel_specs
             )
         record.kernel_id = kernel_id
         self._pending_sessions.update(record)
@@ -306,6 +308,7 @@ def get_kernel_env(
             Here the name is likely to be the name of the associated file
             with the current kernel at startup time.
         """
+        #
         if name is not None:
             cwd = self.kernel_manager.cwd_for_path(path)
             path = os.path.join(cwd, name)
@@ -319,6 +322,7 @@ async def start_kernel_for_session(
         name: Optional[ModelName],
         type: Optional[str],
         kernel_name: Optional[KernelName],
+        custom_kernel_specs: Optional[Dict[str, Any]] = None
     ) -> str:
         """Start a new kernel for a given session.
 
@@ -335,6 +339,8 @@ async def start_kernel_for_session(
             the type of the session
         kernel_name : str
             the name of the kernel specification to use.  The default kernel name will be used if not provided.
+        custom_kernel_specs: dict
+            dictionary of kernek custom specifications
         """
         # allow contents manager to specify kernels cwd
         kernel_path = await ensure_async(self.contents_manager.get_kernel_path(path=path))