diff --git a/esphome/components/template/select/__init__.py b/esphome/components/template/select/__init__.py
index b998a1c2c7..93aa2c8b05 100644
--- a/esphome/components/template/select/__init__.py
+++ b/esphome/components/template/select/__init__.py
@@ -75,7 +75,10 @@ async def to_code(config):
     else:
         cg.add(var.set_optimistic(config[CONF_OPTIMISTIC]))
         initial_option_index = config[CONF_OPTIONS].index(config[CONF_INITIAL_OPTION])
-        cg.add(var.set_initial_option_index(initial_option_index))
+        # Only set if non-zero to avoid bloating setup() function
+        # (initial_option_index_ is zero-initialized in the header)
+        if initial_option_index != 0:
+            cg.add(var.set_initial_option_index(initial_option_index))
 
         if CONF_RESTORE_VALUE in config:
             cg.add(var.set_restore_value(config[CONF_RESTORE_VALUE]))