diff --git a/homeassistant/components/google_generative_ai_conversation/conversation.py b/homeassistant/components/google_generative_ai_conversation/conversation.py
index 12b1e44b3df..3e289fbe16d 100644
--- a/homeassistant/components/google_generative_ai_conversation/conversation.py
+++ b/homeassistant/components/google_generative_ai_conversation/conversation.py
@@ -245,7 +245,8 @@ class GoogleGenerativeAIConversationEntity(
             prompt = "\n".join(
                 (
                     template.Template(
-                        self.entry.options.get(
+                        llm.BASE_PROMPT
+                        + self.entry.options.get(
                             CONF_PROMPT, llm.DEFAULT_INSTRUCTIONS_PROMPT
                         ),
                         self.hass,
diff --git a/homeassistant/components/openai_conversation/conversation.py b/homeassistant/components/openai_conversation/conversation.py
index 7cf4d18cce5..306e4134b9e 100644
--- a/homeassistant/components/openai_conversation/conversation.py
+++ b/homeassistant/components/openai_conversation/conversation.py
@@ -167,7 +167,8 @@ class OpenAIConversationEntity(
                 prompt = "\n".join(
                     (
                         template.Template(
-                            options.get(CONF_PROMPT, llm.DEFAULT_INSTRUCTIONS_PROMPT),
+                            llm.BASE_PROMPT
+                            + options.get(CONF_PROMPT, llm.DEFAULT_INSTRUCTIONS_PROMPT),
                             self.hass,
                         ).async_render(
                             {
diff --git a/homeassistant/helpers/llm.py b/homeassistant/helpers/llm.py
index fc00c4ebac6..ec1bfb7dbc4 100644
--- a/homeassistant/helpers/llm.py
+++ b/homeassistant/helpers/llm.py
@@ -34,10 +34,13 @@ from .singleton import singleton
 
 LLM_API_ASSIST = "assist"
 
+BASE_PROMPT = (
+    'Current time is {{ now().strftime("%X") }}. '
+    'Today\'s date is {{ now().strftime("%x") }}.\n'
+)
+
 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") }}.
 """
 
 
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 40ff556af1c..587586cff17 100644
--- a/tests/components/google_generative_ai_conversation/snapshots/test_conversation.ambr
+++ b/tests/components/google_generative_ai_conversation/snapshots/test_conversation.ambr
@@ -30,10 +30,9 @@
         'history': list([
           dict({
             'parts': '''
+              Current time is 05:00:00. Today's date is 05/24/24.
               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',
@@ -82,10 +81,9 @@
         'history': list([
           dict({
             'parts': '''
+              Current time is 05:00:00. Today's date is 05/24/24.
               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',
@@ -146,10 +144,9 @@
         'history': list([
           dict({
             'parts': '''
+              Current time is 05:00:00. Today's date is 05/24/24.
               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.
               <no_api_prompt>
             ''',
             'role': 'user',
@@ -202,10 +199,9 @@
         'history': list([
           dict({
             'parts': '''
+              Current time is 05:00:00. Today's date is 05/24/24.
               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.
               <no_api_prompt>
             ''',
             'role': 'user',
@@ -258,10 +254,9 @@
         'history': list([
           dict({
             'parts': '''
+              Current time is 05:00:00. Today's date is 05/24/24.
               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.
               <api_prompt>
             ''',
             'role': 'user',
@@ -314,10 +309,9 @@
         'history': list([
           dict({
             'parts': '''
+              Current time is 05:00:00. Today's date is 05/24/24.
               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.
               <api_prompt>
             ''',
             'role': 'user',