diff --git a/src/google/adk/agents/llm_agent.py b/src/google/adk/agents/llm_agent.py
index 0076c6a..302b1bc 100644
--- a/src/google/adk/agents/llm_agent.py
+++ b/src/google/adk/agents/llm_agent.py
@@ -14,6 +14,7 @@
 
 from __future__ import annotations
 
+import inspect
 import logging
 from typing import (
     Any,
@@ -96,7 +97,9 @@ AfterToolCallback: TypeAlias = Union[
     list[_SingleAfterToolCallback],
 ]
 
-InstructionProvider: TypeAlias = Callable[[ReadonlyContext], str]
+InstructionProvider: TypeAlias = Callable[
+    [ReadonlyContext], Union[str, Awaitable[str]]
+]
 
 ToolUnion: TypeAlias = Union[Callable, BaseTool, BaseToolset]
 ExamplesUnion = Union[list[Example], BaseExampleProvider]
@@ -302,7 +305,7 @@ class LlmAgent(BaseAgent):
         ancestor_agent = ancestor_agent.parent_agent
       raise ValueError(f'No model found for {self.name}.')
 
-  def canonical_instruction(self, ctx: ReadonlyContext) -> str:
+  async def canonical_instruction(self, ctx: ReadonlyContext) -> str:
     """The resolved self.instruction field to construct instruction for this agent.
 
     This method is only for use by Agent Development Kit.
@@ -310,9 +313,12 @@ class LlmAgent(BaseAgent):
     if isinstance(self.instruction, str):
       return self.instruction
     else:
-      return self.instruction(ctx)
+      instruction = self.instruction(ctx)
+      if inspect.isawaitable(instruction):
+        instruction = await instruction
+      return instruction
 
-  def canonical_global_instruction(self, ctx: ReadonlyContext) -> str:
+  async def canonical_global_instruction(self, ctx: ReadonlyContext) -> str:
     """The resolved self.instruction field to construct global instruction.
 
     This method is only for use by Agent Development Kit.
@@ -320,7 +326,10 @@ class LlmAgent(BaseAgent):
     if isinstance(self.global_instruction, str):
       return self.global_instruction
     else:
-      return self.global_instruction(ctx)
+      global_instruction = self.global_instruction(ctx)
+      if inspect.isawaitable(global_instruction):
+        global_instruction = await global_instruction
+      return global_instruction
 
   async def canonical_tools(
       self, ctx: ReadonlyContext = None
diff --git a/src/google/adk/flows/llm_flows/instructions.py b/src/google/adk/flows/llm_flows/instructions.py
index 041c867..d2ae683 100644
--- a/src/google/adk/flows/llm_flows/instructions.py
+++ b/src/google/adk/flows/llm_flows/instructions.py
@@ -53,7 +53,7 @@ class _InstructionsLlmRequestProcessor(BaseLlmRequestProcessor):
     if (
         isinstance(root_agent, LlmAgent) and root_agent.global_instruction
     ):  # not empty str
-      raw_si = root_agent.canonical_global_instruction(
+      raw_si = await root_agent.canonical_global_instruction(
           ReadonlyContext(invocation_context)
       )
       si = await _populate_values(raw_si, invocation_context)
@@ -61,7 +61,9 @@ class _InstructionsLlmRequestProcessor(BaseLlmRequestProcessor):
 
     # Appends agent instructions if set.
     if agent.instruction:  # not empty str
-      raw_si = agent.canonical_instruction(ReadonlyContext(invocation_context))
+      raw_si = await agent.canonical_instruction(
+          ReadonlyContext(invocation_context)
+      )
       si = await _populate_values(raw_si, invocation_context)
       llm_request.append_instructions([si])
 
diff --git a/tests/unittests/agents/test_llm_agent_fields.py b/tests/unittests/agents/test_llm_agent_fields.py
index 42ad5ca..a442381 100644
--- a/tests/unittests/agents/test_llm_agent_fields.py
+++ b/tests/unittests/agents/test_llm_agent_fields.py
@@ -92,6 +92,16 @@ def test_canonical_instruction():
   assert agent.canonical_instruction(ctx) == 'instruction: state_value'
 
 
+def test_async_canonical_instruction():
+  async def _instruction_provider(ctx: ReadonlyContext) -> str:
+    return f'instruction: {ctx.state["state_var"]}'
+
+  agent = LlmAgent(name='test_agent', instruction=_instruction_provider)
+  ctx = _create_readonly_context(agent, state={'state_var': 'state_value'})
+
+  assert agent.canonical_instruction(ctx) == 'instruction: state_value'
+
+
 def test_canonical_global_instruction_str():
   agent = LlmAgent(name='test_agent', global_instruction='global instruction')
   ctx = _create_readonly_context(agent)
@@ -114,6 +124,21 @@ def test_canonical_global_instruction():
   )
 
 
+def test_async_canonical_global_instruction():
+  async def _global_instruction_provider(ctx: ReadonlyContext) -> str:
+    return f'global instruction: {ctx.state["state_var"]}'
+
+  agent = LlmAgent(
+      name='test_agent', global_instruction=_global_instruction_provider
+  )
+  ctx = _create_readonly_context(agent, state={'state_var': 'state_value'})
+
+  assert (
+      agent.canonical_global_instruction(ctx)
+      == 'global instruction: state_value'
+  )
+
+
 def test_output_schema_will_disable_transfer(caplog: pytest.LogCaptureFixture):
   with caplog.at_level('WARNING'):
 
diff --git a/tests/unittests/flows/llm_flows/test_instructions.py b/tests/unittests/flows/llm_flows/test_instructions.py
index edc7902..0d2ac5e 100644
--- a/tests/unittests/flows/llm_flows/test_instructions.py
+++ b/tests/unittests/flows/llm_flows/test_instructions.py
@@ -92,6 +92,44 @@ async def test_function_system_instruction():
   )
 
 
+@pytest.mark.asyncio
+async def test_async_function_system_instruction():
+  async def build_function_instruction(
+      readonly_context: ReadonlyContext,
+  ) -> str:
+    return (
+        "This is the function agent instruction for invocation:"
+        f" {readonly_context.invocation_id}."
+    )
+
+  request = LlmRequest(
+      model="gemini-1.5-flash",
+      config=types.GenerateContentConfig(system_instruction=""),
+  )
+  agent = Agent(
+      model="gemini-1.5-flash",
+      name="agent",
+      instruction=build_function_instruction,
+  )
+  invocation_context = utils.create_invocation_context(agent=agent)
+  invocation_context.session = Session(
+      app_name="test_app",
+      user_id="test_user",
+      id="test_id",
+      state={"customerId": "1234567890", "customer_int": 30},
+  )
+
+  async for _ in instructions.request_processor.run_async(
+      invocation_context,
+      request,
+  ):
+    pass
+
+  assert request.config.system_instruction == (
+      "This is the function agent instruction for invocation: test_id."
+  )
+
+
 @pytest.mark.asyncio
 async def test_global_system_instruction():
   sub_agent = Agent(
@@ -128,6 +166,90 @@ async def test_global_system_instruction():
   )
 
 
+@pytest.mark.asyncio
+async def test_function_global_system_instruction():
+  def sub_agent_si(readonly_context: ReadonlyContext) -> str:
+    return "This is the sub agent instruction."
+
+  def root_agent_gi(readonly_context: ReadonlyContext) -> str:
+    return "This is the global instruction."
+
+  sub_agent = Agent(
+      model="gemini-1.5-flash",
+      name="sub_agent",
+      instruction=sub_agent_si,
+  )
+  root_agent = Agent(
+      model="gemini-1.5-flash",
+      name="root_agent",
+      global_instruction=root_agent_gi,
+      sub_agents=[sub_agent],
+  )
+  request = LlmRequest(
+      model="gemini-1.5-flash",
+      config=types.GenerateContentConfig(system_instruction=""),
+  )
+  invocation_context = utils.create_invocation_context(agent=sub_agent)
+  invocation_context.session = Session(
+      app_name="test_app",
+      user_id="test_user",
+      id="test_id",
+      state={"customerId": "1234567890", "customer_int": 30},
+  )
+
+  async for _ in instructions.request_processor.run_async(
+      invocation_context,
+      request,
+  ):
+    pass
+
+  assert request.config.system_instruction == (
+      "This is the global instruction.\n\nThis is the sub agent instruction."
+  )
+
+
+@pytest.mark.asyncio
+async def test_async_function_global_system_instruction():
+  async def sub_agent_si(readonly_context: ReadonlyContext) -> str:
+    return "This is the sub agent instruction."
+
+  async def root_agent_gi(readonly_context: ReadonlyContext) -> str:
+    return "This is the global instruction."
+
+  sub_agent = Agent(
+      model="gemini-1.5-flash",
+      name="sub_agent",
+      instruction=sub_agent_si,
+  )
+  root_agent = Agent(
+      model="gemini-1.5-flash",
+      name="root_agent",
+      global_instruction=root_agent_gi,
+      sub_agents=[sub_agent],
+  )
+  request = LlmRequest(
+      model="gemini-1.5-flash",
+      config=types.GenerateContentConfig(system_instruction=""),
+  )
+  invocation_context = utils.create_invocation_context(agent=sub_agent)
+  invocation_context.session = Session(
+      app_name="test_app",
+      user_id="test_user",
+      id="test_id",
+      state={"customerId": "1234567890", "customer_int": 30},
+  )
+
+  async for _ in instructions.request_processor.run_async(
+      invocation_context,
+      request,
+  ):
+    pass
+
+  assert request.config.system_instruction == (
+      "This is the global instruction.\n\nThis is the sub agent instruction."
+  )
+
+
 @pytest.mark.asyncio
 async def test_build_system_instruction_with_namespace():
   request = LlmRequest(