diff --git a/esphome/components/nextion/base_component.py b/esphome/components/nextion/base_component.py
index 5bd6643cb8..784da35371 100644
--- a/esphome/components/nextion/base_component.py
+++ b/esphome/components/nextion/base_component.py
@@ -33,14 +33,14 @@ CONF_EXIT_REPARSE_ON_START = "exit_reparse_on_start"
 
 
 def NextionName(value):
-    valid_chars = f"{ascii_letters + digits}."
+    valid_chars = f"{ascii_letters + digits + '_'}."
     if not isinstance(value, str) or len(value) > 29:
         raise cv.Invalid("Must be a string less than 29 characters")
 
     for char in value:
         if char not in valid_chars:
             raise cv.Invalid(
-                f"Must only consist of upper/lowercase characters, numbers and the period '.'. The character '{char}' cannot be used."
+                f"Must only consist of upper/lowercase characters, numbers, the underscore '_', and the period '.'. The character '{char}' cannot be used."
             )
 
     return value