Objectives Clinical trials demonstrated that golimumab is effective in anti-TNF naïve patients with ulcerative colitis. We aimed to assess the clinical effectiveness of golimumab in a real-world setting. Materials and methods This was a prospective cohort study, conducted at 16 Swedish hospitals. Data were collected using an electronic case report form. Patients with active ulcerative colitis, defined as Mayo endoscopic subscore ≥2 were eligible for inclusion. The primary outcomes were clinical effectiveness at 12 weeks and 52 weeks, i.e. response (defined as a decrease in Mayo score by ≥3 points or 30% from baseline) and remission (defined as a Mayo score of ≤2 with no individual subscores >1). Results Fifty patients were included. At study entry, 70% were previously exposed to anti-TNF, 16% to vedolizumab, and 96% to immunomodulators. The 12 and 52-week drug continuation rates were 37/50 (74%) and 23/50 (46%), respectively. The 12-week response rate was 14/50 (28%), the remission rate, 8/50 (16%) and the corresponding figures at week 52 were 13/50 (26%) and 10/50 (20%). Among patients who continued golimumab, the median Mayo score decreased from 7 (6–9) at baseline to 1 (0–5) at 52 weeks (p < .01) and the faecal calprotectin decreased from 862 (335–1759) µg/g to 90 (34–169) µg/g (p < .01). Clinical response at week 12 was highly predictive of clinical remission at week 52 (adjusted OR: 73.1; 95% CI: 4.5‒1188.9). Conclusions The majority of golimumab treated patients represented a treatment refractory patient-group. Despite this, our results confirm that golimumab is an effective therapy in ulcerative colitis.