High performance acetone gas sensors were fabricated with molecular imprinted polymers of Ag-LaFeO3 (ALFOMMIPs) and multi walled carbon nanotubes (CNTs) composite using the microwave assisted sol-gel method. The crystalline structure, functional groups, grain size and surface appearance of the synthesized materials were analyzed via different characterization techniques and the gas responses of the samples were examined. The detailed acetone gas sensing tests and analysis revealed that the CNTs and ALFOMIPs nanocomposite (CNT/ALFOMIP) sample possessed a higher response than that of the ALFOMIPs sample. Where 0.75 wt% CNTs were added into the ALFOMIPs (0.75% CNT/ALFOMIP nanocomposite) sensor, an excellent gas sensing performance was exhibited. The response of this sensor was up to 59 for 5 ppm acetone vapors and the response and recovery times were 58 and 33 s at low working temperature of 86 °C, respectively. In addition, it had the best selectivity only to acetone vapors due to the use of the molecular imprinting technique.