This work reports on the design, fabrication and characterization of an inkjet-printed multisensing platform on flexible polymeric substrates integrated into a printed semi-passive high frequency radio frequency identification (HF RFID) smart label. The printed platform was integrated after fabrication to the main RFID carrier, which contained an NFC RFID chip, a microprocessor, a readout frontend and a screen-printed circuitry and antenna. The multisensing platform has channels for capacitive vapor detection (i.e. humidity), two channels for resistive-based vapor detection (i.e. ammonia) with heating capability, and one resistive channel for temperature detection (RTD). A modular approach was employed where the sensing platform was integrated to the base RFID label carrier using foil-to-foil integration techniques compatible with large area fabrication. Besides wireless communication, the semi-passive label possesses data logging and the possibility of measuring all the sensors simultaneously through a direct readout circuitry. In addition to individual sensor characterization, the full functionality of the smart label was successfully demonstrated by measuring different temperature, humidity and ammonia levels.