n this study, the implementation of a sensor node monitoring system based on the MQTT protocolis presented. The sensor node is made using the NodeMCU ESP8266 which is connected to thesensor to measure temperature, humidity, gas levels, and the presence of fire. Nodered is used tobuild a monitoring system. In this study, four connected sensor nodes were used. The MQTTprotocol is implemented on both sides of the sensor node and monitoring system. The sensor nodewill act as a publisher and the monitoring system will act as a subscriber. The sensor dataobtained will be sent to the monitoring system using the MQTT protocol. The test results showedthat the MQTT protocol was successfully implemented. Data from all sensor nodes can bedisplayed on the monitoring systemPada penelitian ini dipresentasikan implementasi sistem monitoring sensor node berbasisprotocol MQTT. Sensor node dibuat menggunakan NodeMCU ESP8266 yang terhubung kesensor untuk mengukur suhu, kelembapan udara, kadar gas, dan keberadaan api. Nodereddigunakan untuk membangun sistem monitoring, Pada penelitian ini digunakan empat buahsensor node yang saling terhubung. Protokol MQTT diimplementasikan pada kedua sisi sensornode dan sistem monitoring. Sensor node akan bertindak sebagai publisher dan sistemmonitoring bertindak sebagai subscriber. Data sensor yang didapat akan dikirimkan ke sistemmonitoring menggunakan protocol MQTT. Hasil pengujian didapatkan bahwa protocol MQTTberhasil diimplementasikan. Data dari seluruh sensor node dapat ditampilkan pada sistemmonitoring
