diff --git a/esphome/core/helpers.cpp b/esphome/core/helpers.cpp
index 714a1642f8..d6280fa537 100644
--- a/esphome/core/helpers.cpp
+++ b/esphome/core/helpers.cpp
@@ -279,9 +279,9 @@ std::string str_snake_case(const std::string &str) {
 }
 std::string str_sanitize(const std::string &str) {
   std::string out;
-  std::copy_if(str.begin(), str.end(), std::back_inserter(out), [](const char &c) {
+  std::replace_if(str.begin(), str.end(), [](const char &c) {
     return c == '-' || c == '_' || (c >= '0' && c <= '9') || (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z');
-  });
+  }, '_');
   return out;
 }
 std::string str_snprintf(const char *fmt, size_t len, ...) {
diff --git a/esphome/helpers.py b/esphome/helpers.py
index 4012b2067f..00416b591f 100644
--- a/esphome/helpers.py
+++ b/esphome/helpers.py
@@ -357,6 +357,9 @@ def snake_case(value):
     return value.replace(" ", "_").lower()
 
 
+_DISALLOWED_CHARS = re.compile(r"[^a-zA-Z0-9_]")
+
+
 def sanitize(value):
     """Same behaviour as `helpers.cpp` method `str_sanitize`."""
-    return re.sub("[^-_0-9a-zA-Z]", r"", value)
+    return _DISALLOWED_CHARS.sub("_", value)