Background The impact of obesity on patient-reported outcome (PRO) after total knee arthroplasty (TKA) surgery has demonstrated varying results. We evaluated knee pain, Activity in Daily Life function (ADL), and satisfaction after TKA surgery in patients with and without prior bariatric surgery (BS). Methods Scandinavian Obesity Surgery Registry (SOReg) and the Swedish Knee Arthroplasty Register (SKAR) were used to identify patients operated on with primary TKA for osteoarthritis (OA) between 2009 and 2019 that had a BS within 2 years before the TKA (BS group). These patients were compared to patients with TKA without prior BS (no BS group). The patients filled in the Knee injury and Osteoarthritis Outcome Score (KOOS) preoperatively and one year postoperatively as well as satisfaction with the surgery one year postoperatively. Multiple linear regression analysis was used to evaluate 1-year postoperative KOOS pain and ADL function between the 2 groups. Adjustments were made for sex, age, and preoperative KOOS pain and ADL function respectively. Results Forty-four patients were included in the BS group and 3,525 patients in the no BS group. We found no statistically or clinically significant difference in one-year postoperative KOOS pain and ADL function between the BS group and the no BS group. The majority of the patients in both groups were classified as satisfied or very satisfied one year postoperatively to the TKA. Conclusions Our results indicate that patients without BS prior to the TKA gain similar 1-year outcome in pain, ADL function and satisfaction as patients with prior BS. Graphical abstract