The present study investigates the torsional behaviour of fire-damaged reinforced concrete (RC) solid square beams with and without stainless steel wire mesh (SSWM) strengthening. Six beams with a cross section of 150 × 150 mm and a length of 1300 mm are cast and tested. Two beams are control samples unaffected by fire and unstrengthened, whilst four beams are exposed to fire at 400 °C. Amongst the four fire-affected beams, two are strengthened with SSWM and the remaining two are left as unstrengthened. The test results include torque–twist behaviour, failure patterns, ductility index, initial stiffness, and energy absorption capacity. The test results indicated that fire exposure significantly reduced the strength and initial stiffness of the RC solid square beams. However, the application of SSWM for strengthening restored and even enhanced the strength and initial stiffness of RC beams. This suggests that SSWM strengthening is an effective method for improving the performance of fire-damaged RC beams, thus valuable for maintaining structural safety and functionality in post-fire.