Abstract This paper demonstrated a hybrid SnO2–BNNTs (SnO2 decorated boron nitride nanotubes) for trace ppb-level sensing towards NO2. A facile way is utilized for the synthesis of SnO2–BNNTs in which BNNTs are consistently coated with SnO2 nanoparticles (NPs). The existence of SnO2 NPs onto BNNTs was confirmed by XRD, XPS, FESEM, and TEM. Sensing characteristics of SnO2–BNNTs sensor, including the sensor response, repeatability, long-term stability, and response–recovery times were studied by exposure to several NO2 gas concentrations varying from 250 ppb to 5 ppm at different operating temperatures form 25 °C–300 °C. As a result, the SnO2–BNNTs sensor showed an extremely low detection limit (DL) of 250 ppb, as well as a better sensor response as compared to the SnO2 sensor. The maximum sensor response of SnO2–BNNTs sensor was ∼2610 towards 5 ppm NO2 gas at low operating temperature (100 °C). Expanded variation of space charge depleted regions was created at p-n heterojunction which promoted tunneling effect caused by entrapment of NO2 gas molecule and offered conducting channels (CCs) through BNNTs for charge carriers towards an improved sensor response of SnO2–BNNTs sensor.