Background: Severe bilateral Fixed flexion deformity of the knees resulting from irreversible joint damage is a disabling complication of long-standing rheumatoid arthritis, associated with loss of ambulatory ability. While Total knee Arthroplasty is an effective treatment for such patients, it poses significant intra-operative technical demands and challenges with post-operative rehabilitation. Method: We report a case of Severe Fixed flexion deformity of both knees in a 46-year-old male with long-standing rheumatoid arthritis, non-ambulatory since 5 years, treated by sequential total knee arthroplasty. Results: Treating Severe bilateral Fixed flexion deformities in a non-ambulatory patient by sequential total knee Arthroplasty using standard implants yielded complete deformity correction and pain-free restoration of active range of motion in both knees with stable independent ambulation and complete restoration of lower limb function within 3 months of surgery. Conclusion: Our case is particularly remarkable for complete restoration of stable, pain-free restoration of ambulation within 3months in a patient with severe bilateral knee fixed flexion deformities who had been non-ambulatory for 5 years preceding his bilateral sequential total knee arthroplasty. Keywords: Fixed flexion deformity, Total knee arthroplasty, Common peroneal nerve, Rheumatoid arthritis.