Ammonia (NH3) and hydrazine (N2H4) are both utilized within a wide range of chemical industry, agriculture and pharmaceuticals. A detection strategy is realized for the identification of gaseous NH3 and N2H4, adopting the host-guest complexation between AIE-active molecule TPM and cucurbit8uril (CB8). The TPM@CB8 complex exhibits a deep red emission, which is immediately turned into light yellow and sky-blue as meeting with gaseous NH3 and N2H4, respectively. This newly reported TPM@CB8 complex is capable of sensitively and selectively detecting gaseous NH3 and N2H4 with a low detection limit (0.80 ppm and 0.41 ppm). The sensing mechanism is studied with 1H NMR, HRMS, SEM and DFT calculations. Finally, TPM@CB8 complex could detect N2H4 vapor from real water samples, and act as a food spoilage sensor for monitoring gaseous NH3 generated in food spoilage. A novel host-guest complex TPM@CB8 formed between AIEgen TPM and CB8 has been reported, which exhibited the dual fluorescence response toward gaseous N2H4 and NH3 on glass plate. Display omitted •A novel host-guest complex TPM@CB8 was explored.•This complex could simultaneously sense gaseous NH3 and N2H4 on glass plate.•The sensing sensitivity of this complex was much higher than most other probes.•This complex was able to detect gaseous NH3 and N2H4 in real samples.