diff --git a/homeassistant/components/google_generative_ai_conversation/config_flow.py b/homeassistant/components/google_generative_ai_conversation/config_flow.py
index ef700d289c7..b373239665d 100644
--- a/homeassistant/components/google_generative_ai_conversation/config_flow.py
+++ b/homeassistant/components/google_generative_ai_conversation/config_flow.py
@@ -43,7 +43,6 @@ from .const import (
     CONF_TEMPERATURE,
     CONF_TOP_K,
     CONF_TOP_P,
-    DEFAULT_PROMPT,
     DOMAIN,
     RECOMMENDED_CHAT_MODEL,
     RECOMMENDED_HARM_BLOCK_THRESHOLD,
@@ -64,7 +63,7 @@ STEP_API_DATA_SCHEMA = vol.Schema(
 RECOMMENDED_OPTIONS = {
     CONF_RECOMMENDED: True,
     CONF_LLM_HASS_API: llm.LLM_API_ASSIST,
-    CONF_PROMPT: DEFAULT_PROMPT,
+    CONF_PROMPT: llm.DEFAULT_INSTRUCTIONS_PROMPT,
 }
 
 
@@ -224,7 +223,11 @@ async def google_generative_ai_config_option_schema(
     schema = {
         vol.Optional(
             CONF_PROMPT,
-            description={"suggested_value": options.get(CONF_PROMPT, DEFAULT_PROMPT)},
+            description={
+                "suggested_value": options.get(
+                    CONF_PROMPT, llm.DEFAULT_INSTRUCTIONS_PROMPT
+                )
+            },
         ): TemplateSelector(),
         vol.Optional(
             CONF_LLM_HASS_API,
diff --git a/homeassistant/components/google_generative_ai_conversation/const.py b/homeassistant/components/google_generative_ai_conversation/const.py
index a83ffed2d88..bd60e8d94c1 100644
--- a/homeassistant/components/google_generative_ai_conversation/const.py
+++ b/homeassistant/components/google_generative_ai_conversation/const.py
@@ -5,7 +5,6 @@ import logging
 DOMAIN = "google_generative_ai_conversation"
 LOGGER = logging.getLogger(__package__)
 CONF_PROMPT = "prompt"
-DEFAULT_PROMPT = "Answer in plain text. Keep it simple and to the point."
 
 CONF_RECOMMENDED = "recommended"
 CONF_CHAT_MODEL = "chat_model"
diff --git a/homeassistant/components/google_generative_ai_conversation/conversation.py b/homeassistant/components/google_generative_ai_conversation/conversation.py
index ed50ed69a02..d6f7981fc8c 100644
--- a/homeassistant/components/google_generative_ai_conversation/conversation.py
+++ b/homeassistant/components/google_generative_ai_conversation/conversation.py
@@ -32,7 +32,6 @@ from .const import (
     CONF_TEMPERATURE,
     CONF_TOP_K,
     CONF_TOP_P,
-    DEFAULT_PROMPT,
     DOMAIN,
     LOGGER,
     RECOMMENDED_CHAT_MODEL,
@@ -226,7 +225,10 @@ class GoogleGenerativeAIConversationEntity(
             prompt = "\n".join(
                 (
                     template.Template(
-                        self.entry.options.get(CONF_PROMPT, DEFAULT_PROMPT), self.hass
+                        self.entry.options.get(
+                            CONF_PROMPT, llm.DEFAULT_INSTRUCTIONS_PROMPT
+                        ),
+                        self.hass,
                     ).async_render(
                         {
                             "ha_name": self.hass.config.location_name,
diff --git a/homeassistant/components/openai_conversation/config_flow.py b/homeassistant/components/openai_conversation/config_flow.py
index 09b909b3d5e..9a2b1b6fa79 100644
--- a/homeassistant/components/openai_conversation/config_flow.py
+++ b/homeassistant/components/openai_conversation/config_flow.py
@@ -34,7 +34,6 @@ from .const import (
     CONF_RECOMMENDED,
     CONF_TEMPERATURE,
     CONF_TOP_P,
-    DEFAULT_PROMPT,
     DOMAIN,
     RECOMMENDED_CHAT_MODEL,
     RECOMMENDED_MAX_TOKENS,
@@ -53,7 +52,7 @@ STEP_USER_DATA_SCHEMA = vol.Schema(
 RECOMMENDED_OPTIONS = {
     CONF_RECOMMENDED: True,
     CONF_LLM_HASS_API: llm.LLM_API_ASSIST,
-    CONF_PROMPT: DEFAULT_PROMPT,
+    CONF_PROMPT: llm.DEFAULT_INSTRUCTIONS_PROMPT,
 }
 
 
@@ -170,7 +169,11 @@ def openai_config_option_schema(
     schema = {
         vol.Optional(
             CONF_PROMPT,
-            description={"suggested_value": options.get(CONF_PROMPT, DEFAULT_PROMPT)},
+            description={
+                "suggested_value": options.get(
+                    CONF_PROMPT, llm.DEFAULT_INSTRUCTIONS_PROMPT
+                )
+            },
         ): TemplateSelector(),
         vol.Optional(
             CONF_LLM_HASS_API,
diff --git a/homeassistant/components/openai_conversation/const.py b/homeassistant/components/openai_conversation/const.py
index 995d80e02f1..f362f4278a1 100644
--- a/homeassistant/components/openai_conversation/const.py
+++ b/homeassistant/components/openai_conversation/const.py
@@ -7,7 +7,6 @@ LOGGER = logging.getLogger(__package__)
 
 CONF_RECOMMENDED = "recommended"
 CONF_PROMPT = "prompt"
-DEFAULT_PROMPT = """Answer in plain text. Keep it simple and to the point."""
 CONF_CHAT_MODEL = "chat_model"
 RECOMMENDED_CHAT_MODEL = "gpt-4o"
 CONF_MAX_TOKENS = "max_tokens"
diff --git a/homeassistant/components/openai_conversation/conversation.py b/homeassistant/components/openai_conversation/conversation.py
index eb2f0911a20..ab76d9cfb56 100644
--- a/homeassistant/components/openai_conversation/conversation.py
+++ b/homeassistant/components/openai_conversation/conversation.py
@@ -23,7 +23,6 @@ from .const import (
     CONF_PROMPT,
     CONF_TEMPERATURE,
     CONF_TOP_P,
-    DEFAULT_PROMPT,
     DOMAIN,
     LOGGER,
     RECOMMENDED_CHAT_MODEL,
@@ -143,7 +142,8 @@ class OpenAIConversationEntity(
                 prompt = "\n".join(
                     (
                         template.Template(
-                            options.get(CONF_PROMPT, DEFAULT_PROMPT), self.hass
+                            options.get(CONF_PROMPT, llm.DEFAULT_INSTRUCTIONS_PROMPT),
+                            self.hass,
                         ).async_render(
                             {
                                 "ha_name": self.hass.config.location_name,
diff --git a/homeassistant/helpers/llm.py b/homeassistant/helpers/llm.py
index e09af97620c..e81c62ae25c 100644
--- a/homeassistant/helpers/llm.py
+++ b/homeassistant/helpers/llm.py
@@ -23,6 +23,12 @@ from .singleton import singleton
 
 LLM_API_ASSIST = "assist"
 
+DEFAULT_INSTRUCTIONS_PROMPT = """You are a voice assistant for Home Assistant.
+Answer in plain text. Keep it simple and to the point.
+The current time is {{ now().strftime("%X") }}.
+Today's date is {{ now().strftime("%x") }}.
+"""
+
 
 @callback
 def async_render_no_api_prompt(hass: HomeAssistant) -> str:
diff --git a/tests/components/google_generative_ai_conversation/snapshots/test_conversation.ambr b/tests/components/google_generative_ai_conversation/snapshots/test_conversation.ambr
index 6d37c1d1823..6ffe3d747d3 100644
--- a/tests/components/google_generative_ai_conversation/snapshots/test_conversation.ambr
+++ b/tests/components/google_generative_ai_conversation/snapshots/test_conversation.ambr
@@ -30,7 +30,10 @@
         'history': list([
           dict({
             'parts': '''
+              You are a voice assistant for Home Assistant.
               Answer in plain text. Keep it simple and to the point.
+              The current time is 05:00:00.
+              Today's date is 05/24/24.
               Only if the user wants to control a device, tell them to edit the AI configuration and allow access to Home Assistant.
             ''',
             'role': 'user',
@@ -79,7 +82,10 @@
         'history': list([
           dict({
             'parts': '''
+              You are a voice assistant for Home Assistant.
               Answer in plain text. Keep it simple and to the point.
+              The current time is 05:00:00.
+              Today's date is 05/24/24.
               Only if the user wants to control a device, tell them to edit the AI configuration and allow access to Home Assistant.
             ''',
             'role': 'user',
@@ -140,7 +146,10 @@
         'history': list([
           dict({
             'parts': '''
+              You are a voice assistant for Home Assistant.
               Answer in plain text. Keep it simple and to the point.
+              The current time is 05:00:00.
+              Today's date is 05/24/24.
               Only if the user wants to control a device, tell them to edit the AI configuration and allow access to Home Assistant.
             ''',
             'role': 'user',
@@ -193,7 +202,10 @@
         'history': list([
           dict({
             'parts': '''
+              You are a voice assistant for Home Assistant.
               Answer in plain text. Keep it simple and to the point.
+              The current time is 05:00:00.
+              Today's date is 05/24/24.
               Only if the user wants to control a device, tell them to edit the AI configuration and allow access to Home Assistant.
             ''',
             'role': 'user',
@@ -246,7 +258,10 @@
         'history': list([
           dict({
             'parts': '''
+              You are a voice assistant for Home Assistant.
               Answer in plain text. Keep it simple and to the point.
+              The current time is 05:00:00.
+              Today's date is 05/24/24.
               Call the intent tools to control Home Assistant. Just pass the name to the intent.
             ''',
             'role': 'user',
@@ -299,7 +314,10 @@
         'history': list([
           dict({
             'parts': '''
+              You are a voice assistant for Home Assistant.
               Answer in plain text. Keep it simple and to the point.
+              The current time is 05:00:00.
+              Today's date is 05/24/24.
               Call the intent tools to control Home Assistant. Just pass the name to the intent.
             ''',
             'role': 'user',
diff --git a/tests/components/google_generative_ai_conversation/test_config_flow.py b/tests/components/google_generative_ai_conversation/test_config_flow.py
index 805fb9c3c74..77da95506fa 100644
--- a/tests/components/google_generative_ai_conversation/test_config_flow.py
+++ b/tests/components/google_generative_ai_conversation/test_config_flow.py
@@ -7,6 +7,9 @@ from google.rpc.error_details_pb2 import ErrorInfo
 import pytest
 
 from homeassistant import config_entries
+from homeassistant.components.google_generative_ai_conversation.config_flow import (
+    RECOMMENDED_OPTIONS,
+)
 from homeassistant.components.google_generative_ai_conversation.const import (
     CONF_CHAT_MODEL,
     CONF_DANGEROUS_BLOCK_THRESHOLD,
@@ -19,7 +22,6 @@ from homeassistant.components.google_generative_ai_conversation.const import (
     CONF_TEMPERATURE,
     CONF_TOP_K,
     CONF_TOP_P,
-    DEFAULT_PROMPT,
     DOMAIN,
     RECOMMENDED_CHAT_MODEL,
     RECOMMENDED_HARM_BLOCK_THRESHOLD,
@@ -30,7 +32,6 @@ from homeassistant.components.google_generative_ai_conversation.const import (
 from homeassistant.const import CONF_LLM_HASS_API
 from homeassistant.core import HomeAssistant
 from homeassistant.data_entry_flow import FlowResultType
-from homeassistant.helpers import llm
 
 from tests.common import MockConfigEntry
 
@@ -92,11 +93,7 @@ async def test_form(hass: HomeAssistant) -> None:
     assert result2["data"] == {
         "api_key": "bla",
     }
-    assert result2["options"] == {
-        CONF_RECOMMENDED: True,
-        CONF_LLM_HASS_API: llm.LLM_API_ASSIST,
-        CONF_PROMPT: DEFAULT_PROMPT,
-    }
+    assert result2["options"] == RECOMMENDED_OPTIONS
     assert len(mock_setup_entry.mock_calls) == 1
 
 
diff --git a/tests/components/google_generative_ai_conversation/test_conversation.py b/tests/components/google_generative_ai_conversation/test_conversation.py
index 4c208c240b8..1f11cc58705 100644
--- a/tests/components/google_generative_ai_conversation/test_conversation.py
+++ b/tests/components/google_generative_ai_conversation/test_conversation.py
@@ -2,6 +2,7 @@
 
 from unittest.mock import AsyncMock, MagicMock, patch
 
+from freezegun import freeze_time
 from google.api_core.exceptions import GoogleAPICallError
 import google.generativeai.types as genai_types
 import pytest
@@ -23,6 +24,13 @@ from homeassistant.helpers import (
 from tests.common import MockConfigEntry
 
 
+@pytest.fixture(autouse=True)
+def freeze_the_time():
+    """Freeze the time."""
+    with freeze_time("2024-05-24 12:00:00", tz_offset=0):
+        yield
+
+
 @pytest.mark.parametrize(
     "agent_id", [None, "conversation.google_generative_ai_conversation"]
 )
diff --git a/tests/components/openai_conversation/test_config_flow.py b/tests/components/openai_conversation/test_config_flow.py
index 234e518b3c5..f5017c124b1 100644
--- a/tests/components/openai_conversation/test_config_flow.py
+++ b/tests/components/openai_conversation/test_config_flow.py
@@ -7,6 +7,7 @@ from openai import APIConnectionError, AuthenticationError, BadRequestError
 import pytest
 
 from homeassistant import config_entries
+from homeassistant.components.openai_conversation.config_flow import RECOMMENDED_OPTIONS
 from homeassistant.components.openai_conversation.const import (
     CONF_CHAT_MODEL,
     CONF_MAX_TOKENS,
@@ -62,6 +63,7 @@ async def test_form(hass: HomeAssistant) -> None:
     assert result2["data"] == {
         "api_key": "bla",
     }
+    assert result2["options"] == RECOMMENDED_OPTIONS
     assert len(mock_setup_entry.mock_calls) == 1