Whether simultaneous bilateral TKAs (SBTKAs) are more painful and the postoperative functional recovery slower compared to staged bilateral TKAs or unilateral TKAs are issues that frequently concerns patients. The purpose of the current study was to compare the early postoperative pain, function and recovery in simultaneous bilateral versus unilateral computer-assisted TKA. In this prospective study, 50 consecutive patients undergoing unilateral computer-assisted total knee arthroplasties (TKAs) were compared with 50 consecutive patients undergoing SBTKAs in terms of pain, length of hospital stay and rehabilitative milestones during the immediate postoperative period. The mean visual analogue pain scores, mean knee range of motion, straight leg raising and extensor lag were equal in both the groups at the time of discharge. Patients in the SBTKA group lagged behind the unilateral group in stick walking by approximately 24 h. The results of this study demonstrate excellent pain relief and functional recovery with simultaneous bilateral computer-assisted TKAs comparable to unilateral TKAs. Patients eligible for bilateral TKAs can undergo them simultaneously without excessive pain or slower functional outcome.