Chronic pain is associated with reduced efficiency of cognitive performance, and few studies have investigated methods of remediation. We trialled a computerised cognitive training protocol to determine whether it could attenuate cognitive difficulties in a chronic pain sample. Thirty-nine adults with chronic pain (mean age = 43.3, 61.5% females) were randomised to an 8-week online course (3 sessions/week from home) of game-like cognitive training exercises, or an active control involving watching documentary videos. Participants received weekly supervision by video call. Primary outcomes were a global neurocognitive composite (tests of attention, speed, and executive function) and self-reported cognition. Secondary outcomes were pain (intensity; interference), mood symptoms (depression; anxiety), and coping with pain (catastrophising; self-efficacy). Thirty participants (15 training and 15 control) completed the trial. Mixed model intention-to-treat analyses revealed significant effects of training on the global neurocognitive composite (net effect size [ES] = 0.43, P = 0.017), driven by improved executive function performance (attention switching and working memory). The control group reported improvement in pain intensity (net ES = 0.65, P = 0.022). Both groups reported subjective improvements in cognition (ES = 0.28, P = 0.033) and catastrophising (ES = 0.55, P = 0.006). Depression, anxiety, self-efficacy, and pain interference showed no change in either group. This study provides preliminary evidence that supervised cognitive training may be a viable method for enhancing cognitive skills in persons with chronic pain, but transfer to functional and clinical outcomes remains to be demonstrated. Active control results suggest that activities perceived as relaxing or enjoyable contribute to improved perception of well-being. Weekly contact was pivotal to successful program completion.