Background: Unicondylar knee arthroplasty (UKA) is an effective procedure, which reduces pain, increases range of motion, and improves function. UKA could be performed simultaneously or in staged sessions. This study aimed to compare bilateral cementless UKA performed simultaneously and in staged sessions in terms of complications, hemoglobin levels, transfusions, and functional outcomes. Methods: Patients undergoing bilateral UKA for symptomatic medial compartment osteoarthritis were retrospectively analyzed. Of the 73 patients who met the inclusion criteria, 40 underwent surgery simultaneously and 33 underwent surgery in separate sessions. Operative time, length of hospital stay, change in hemoglobin, need for blood transfusion, complications, and functional outcomes were assessed. Results: There was no statistically significant difference between the two groups in demographic data. Simultaneously operated patients had a significantly shorter hospital stay and shorter operative time. Statistically significant improvements in clinical scores were noted in both groups. The degree of improvement in functional scores did not differ between the groups. There was no difference between the two groups in terms of complication rates, but the number of periprosthetic tibial fractures was higher in the simultaneous group. Conclusions Simultaneous bilateral cementless UKA was more advantageous in terms of cumulative hospital stay and total operation time with similar clinical results when compared to a staged procedure. While the overall complication rate was similar, the rate of periprosthetic fractures was 5% in the simultaneous group.