Abstract Background To evaluate the real-world effect of the IL-12/23 inhibitor ustekinumab or of a tumour necrosis factor inhibitor (TNFi) on patient-reported outcomes (PRO) and their association with effectiveness endpoints in psoriatic arthritis (PsA) patients over 3 years. Methods In PsABio (NCT02627768), a prospective, observational study, patients with PsA that were prescribed first- to third-line ustekinumab or a TNFi, and remained on that drug for 3 years, were analysed for change in baseline in PROs (EuroQol-5 dimensions health state VAS [EQ-5D VAS], 12-item Psoriatic Arthritis Impact of Disease questionnaire [PsAID-12; range 0–10], Work Productivity and Activity Impairment for Psoriatic Arthritis questionnaire [WPAI; results expressed as a percentage for each domain]), and the association between PROs and WPAI with effectiveness endpoints, clinical disease activity index for psoriatic arthritis (cDAPSA), low disease activity (LDA)/remission, minimal disease activity (MDA) and very low disease activity (VLDA). Results In 437 patients (mean age 49.1 years, 47.8% female), at 3 years, ustekinumab and TNFi treatment led to comparable improvements in EQ-5D VAS; mean change from baseline (95% confidence intervals [CI]) was 11.0 (6.5; 15.4) and 18.9 (14.0; 23.9), respectively. Both groups improved PsAID-12 after 3 years; mean change from baseline (95% CI) was −2.9 (−3.2; −2.5) and −3.5 (−3.9; −3.2), respectively. At baseline, due to their PsA, TNFi-treated patients had lower work productivity compared to ustekinumab-treated patients; mean productivity reduction (95% CI) was 58.8 [52.4; 65.2] and 43.3 [35.6; 51.1]. Over 3 years, TNFi-treated patients had a greater improvement in work productivity compared to ustekinumab-treated patients, ultimately leaving work productivity to be comparable between groups; mean improvement (95% CI) was 44.5% (38.4; 50.6) and 24.9% (15.8; 34.0), respectively. A similar trend was observed in activity impairment. Patients in both treatment groups who achieved effectiveness endpoints, cDAPSA LDA/remission, MDA, and VLDA had greater improvement in PROs and WPAI than patients who did not achieve these endpoints. Conclusions At 3 years, improvements in PROs following ustekinumab or TNFi treatment were generally comparable; however, TNFi-treated patients achieved a greater improvement in work productivity, although this group started from a lower baseline. Achievement of effectiveness endpoints, independent of treatment group, also improved PROs. Trial registration ClinicalTrials.gov, NCT02627768. Registered on 11 December 2015