Highly sensitive and stable acetone gas sensors based on MEMS substrate supported carbon nanoparticles decorated mesoporous α-Fe₂O₃ (C-d-mFe₂O₃) nanorods (NRs) derived from Fe-MIL-88B-NH₂ NRs were first synthesized via a sequential process including a facile hydrothermal reaction and one-step pyrolysis at a moderate temperature in air. The MEMS architecture ensures low power consumption, small size, and high integration of the sensor. The obtained C-d-mFe₂O₃ NRs exhibit good thermal stability and superior acetone sensing performance with excellent response (R_a/R_g = 5.2 to 2.5 ppm) and selectivity, fast response/recovery speed (10/27 s), and low detection limit of 500 ppb at 225 °C. Furthermore, the acetone sensor exhibits remarkable long-term stability and repeatability even after being stored in air for over 10 months. The enhanced acetone sensing performance could be attributed to the large specific surface area of mesoporous α-Fe₂O₃ NRs, highly conductive carbon nanoparticles on the surface, and the formation of α-Fe₂O₃/C heterojunction. Density functional theory (DFT) calculations help to further confirm the superior acetone sensing performance. The competitive performance makes C-d-mFe₂O₃ NRs gas sensor a great potential for practical application in environmental harmful acetone gas monitoring.