Adults with chronic pain who also report high pain intensity and disability are more likely to experience depression and anxiety symptoms. The current study examined changes in anxiety and depression symptoms after an internet-delivered pain management program based on baseline pain intensity and disability severity categories. In a secondary analysis of data from four randomised controlled trials (n = 1333), greater pain intensity and disability were associated with increased odds of elevated anxiety or depression symptoms at baseline. Treatment led to greater reductions in anxiety and depression symptoms compared to a waitlist control, and these improvements occurred irrespective of baseline pain intensity or disability severity. Those individuals who reported ≥ 30% improvements in pain intensity or disability at post-treatment were more likely to also report ≥ 30% improvements in psychological symptoms. Importantly, most participants who achieved ≥ 30% improvements in depression and anxiety had not experienced such improvements in pain intensity or disability. These findings suggest that emerging internet-delivered pain management programs can lead to reductions in psychological distress even when pain intensity and disability are severe or do not improve with treatment. This indicates the value of such treatments in treating distress and improving mental health in people with chronic pain.