diff --git a/esphome/core/helpers.h b/esphome/core/helpers.h
index 9bd1f436c1..0a6ef1bf70 100644
--- a/esphome/core/helpers.h
+++ b/esphome/core/helpers.h
@@ -698,8 +698,11 @@ inline char *int8_to_str(char *buf, int8_t val) {
   if (v >= 100) {
     *buf++ = '1';  // int8 max is 128, so hundreds digit is always 1
     v -= 100;
-  }
-  if (v >= 10) {
+    // Must write tens digit (even if 0) after hundreds
+    int tens = v / 10;
+    *buf++ = '0' + tens;
+    v -= tens * 10;
+  } else if (v >= 10) {
     int tens = v / 10;
     *buf++ = '0' + tens;
     v -= tens * 10;