diff --git a/esphome/components/api/__init__.py b/esphome/components/api/__init__.py
index f4c1b2b0bd..4d6a116e67 100644
--- a/esphome/components/api/__init__.py
+++ b/esphome/components/api/__init__.py
@@ -530,17 +530,23 @@ async def homeassistant_service_to_code(
     # Initialize FixedVectors with exact sizes from config
     cg.add(var.init_data(len(config[CONF_DATA])))
     for key, value in config[CONF_DATA].items():
-        templ = await cg.templatable(value, args, cg.std_string)
+        # output_type=None because lambdas can return non-string types (int,
+        # float, char*) that TemplatableStringValue converts via to_string.
+        # Static strings are manually wrapped for PROGMEM on ESP8266.
+        templ = await cg.templatable(value, args, None)
+        if isinstance(templ, str):
+            templ = cg.FlashStringLiteral(templ)
         cg.add(var.add_data(cg.FlashStringLiteral(key), templ))
 
     cg.add(var.init_data_template(len(config[CONF_DATA_TEMPLATE])))
     for key, value in config[CONF_DATA_TEMPLATE].items():
-        templ = await cg.templatable(value, args, cg.std_string)
+        templ = await cg.templatable(value, args, None)
+        if isinstance(templ, str):
+            templ = cg.FlashStringLiteral(templ)
         cg.add(var.add_data_template(cg.FlashStringLiteral(key), templ))
 
     cg.add(var.init_variables(len(config[CONF_VARIABLES])))
     for key, value in config[CONF_VARIABLES].items():
-        # Variables can return any type (float, int, etc.), not just strings
         templ = await cg.templatable(value, args, None)
         cg.add(var.add_variable(cg.FlashStringLiteral(key), templ))
 
@@ -616,17 +622,23 @@ async def homeassistant_event_to_code(config, action_id, template_arg, args):
     # Initialize FixedVectors with exact sizes from config
     cg.add(var.init_data(len(config[CONF_DATA])))
     for key, value in config[CONF_DATA].items():
-        templ = await cg.templatable(value, args, cg.std_string)
+        # output_type=None because lambdas can return non-string types (int,
+        # float, char*) that TemplatableStringValue converts via to_string.
+        # Static strings are manually wrapped for PROGMEM on ESP8266.
+        templ = await cg.templatable(value, args, None)
+        if isinstance(templ, str):
+            templ = cg.FlashStringLiteral(templ)
         cg.add(var.add_data(cg.FlashStringLiteral(key), templ))
 
     cg.add(var.init_data_template(len(config[CONF_DATA_TEMPLATE])))
     for key, value in config[CONF_DATA_TEMPLATE].items():
-        templ = await cg.templatable(value, args, cg.std_string)
+        templ = await cg.templatable(value, args, None)
+        if isinstance(templ, str):
+            templ = cg.FlashStringLiteral(templ)
         cg.add(var.add_data_template(cg.FlashStringLiteral(key), templ))
 
     cg.add(var.init_variables(len(config[CONF_VARIABLES])))
     for key, value in config[CONF_VARIABLES].items():
-        # Variables can return any type (float, int, etc.), not just strings
         templ = await cg.templatable(value, args, None)
         cg.add(var.add_variable(cg.FlashStringLiteral(key), templ))