diff --git a/google/cloud/bigtable/data/_async/client.py b/google/cloud/bigtable/data/_async/client.py
index d560d7e1e..a4390bf74 100644
--- a/google/cloud/bigtable/data/_async/client.py
+++ b/google/cloud/bigtable/data/_async/client.py
@@ -472,6 +472,7 @@ def get_table(self, instance_id: str, table_id: str, *args, **kwargs) -> TableAs
             table_id: The ID of the table. table_id is combined with the
                 instance_id and the client's project to fully specify the table
             app_profile_id: The app profile to associate with requests.
+                If not set, will use "default".
                 https://cloud.google.com/bigtable/docs/app-profiles
             default_read_rows_operation_timeout: The default timeout for read rows
                 operations, in seconds. If not set, defaults to 600 seconds (10 minutes)
@@ -542,6 +543,7 @@ async def execute_query(
                 detected automatically (i.e. the value can be None, an empty list or
                 an empty dict).
             app_profile_id: The app profile to associate with requests.
+                If not set, will use "default".
                 https://cloud.google.com/bigtable/docs/app-profiles
             operation_timeout: the time budget for the entire operation, in seconds.
                 Failed requests will be retried within the budget.
@@ -571,6 +573,8 @@ async def execute_query(
         pb_params = _format_execute_query_params(parameters, parameter_types)
 
         instance_name = self._gapic_client.instance_path(self.project, instance_id)
+        if app_profile_id is None:
+            app_profile_id = "default"
 
         request_body = {
             "instance_name": instance_name,
@@ -662,6 +666,7 @@ def __init__(
             table_id: The ID of the table. table_id is combined with the
                 instance_id and the client's project to fully specify the table
             app_profile_id: The app profile to associate with requests.
+                If not set, will use "default".
                 https://cloud.google.com/bigtable/docs/app-profiles
             default_read_rows_operation_timeout: The default timeout for read rows
                 operations, in seconds. If not set, defaults to 600 seconds (10 minutes)
@@ -713,7 +718,9 @@ def __init__(
         self.table_name = self.client._gapic_client.table_path(
             self.client.project, instance_id, table_id
         )
-        self.app_profile_id = app_profile_id
+        self.app_profile_id = (
+            app_profile_id if app_profile_id is not None else "default"
+        )
 
         self.default_operation_timeout = default_operation_timeout
         self.default_attempt_timeout = default_attempt_timeout