The most common pattern seen in bilateral knee osteoarthritis involves only the medial compartment in both knees. In such cases, bilateral Unicompartmental Knee Arthroplasty (UKA) would be a suitable surgery, this can be done simultaneously in one surgery or in stages with a period of time between each UKA. Simultaneous bilateral UKA in appropriately selected patients have the potential advantages of a lower cost, a shorter hospital stay, and a shorter overall recovery process. Despite this, there are concerns that operating on both knees in one surgery may increase the risk of complications, revisions and mortality. A PRISMA systematic review and meta-analysis was conducted using three databases (MEDLINE, EMBASE, and Scopus) to identify all studies which investigated either clinical or radiological outcomes in simultaneous bilateral UKA. All sixteen studies included found that simultaneous bilateral UKA improved clinical and radiological outcomes. Eight studies compared clinical or radiological outcomes between simultaneous and staged bilateral UKA. Simultaneous bilateral UKA was found to have a significantly shorter length of operation, length of hospital stay, and a lower treatment cost (P < 0.001). Our meta-analysis found no statistically significant difference in the all-cause complication rate between simultaneous and staged bilateral UKA (P = 0.36). Only one study compared radiological outcomes between simultaneous and staged bilateral UKA which found no significant difference. Our review suggests that simultaneous bilateral UKA is comparable to staged bilateral UKA in terms of clinical and radiological outcomes and has the potential to be increasingly adopted in clinical practice due to its superior cost-effectiveness.