One hundred and sixty-four patients (179 UKAs) with a mean age of 62.3 years responded at an average follow-up of 20.2 months. Preoperatively, 132 patients (81%) participated in sports, which increased to 147 patients (90%) after UKA. Analyzing outcomes for each knee individually, satisfaction with return to sports was recorded in 83% (149/179). Return to a higher or similar level was reported in 85.4% of the cases (117/137). Most common sports after UKA were cycling (45%), swimming (38%), and stationary cycling (27%). Overall, 93.9% of patients were able to return to low impact sports, 63.9% to intermediate and 32.7% to high impact sports. Regarding activity scores, preoperative NRS score improved from 6.40 ± 2.10 to 1.33 ± 1.73 postoperatively (p < .001). The mean preoperative UCLA score improved from 5.93 ± 2.19 to 6.78 ± 1.92 (p < .001) and HAAS score from 9.13 ± 3.55 to 11.08 ± 2.83 postoperatively (p < .001). Regression analyses showed that male sex, preoperative UCLA score and sports participation predicted high activity scores postoperatively.