diff --git a/esphome/components/esp32_ble_client/ble_client_base.h b/esphome/components/esp32_ble_client/ble_client_base.h
index 38fd6a5ba4..1e4b015824 100644
--- a/esphome/components/esp32_ble_client/ble_client_base.h
+++ b/esphome/components/esp32_ble_client/ble_client_base.h
@@ -43,7 +43,7 @@ class BLEClientBase : public espbt::ESPBTClient, public Component {
       memset(this->remote_bda_, 0, sizeof(this->remote_bda_));
       this->address_str_ = "";
     } else {
-      this->address_str_ = str_snprintf("%02x:%02x:%02x:%02x:%02x:%02x", 17, (uint8_t)(this->address_ >> 40) & 0xff,
+      this->address_str_ = str_snprintf("%02X:%02X:%02X:%02X:%02X:%02X", 17, (uint8_t)(this->address_ >> 40) & 0xff,
                                         (uint8_t)(this->address_ >> 32) & 0xff, (uint8_t)(this->address_ >> 24) & 0xff,
                                         (uint8_t)(this->address_ >> 16) & 0xff, (uint8_t)(this->address_ >> 8) & 0xff,
                                         (uint8_t)(this->address_ >> 0) & 0xff);