Objective: Although physical activity is an evidence-based intervention that reduces disease-related symptoms and comorbidity in rheumatoid arthritis (RA), the effect of physical activity on self-reported function and quality of life (QoL) has not yet been analyzed. The present study synthesizes the evidence for the effectiveness of physical activity on QoL and self-reported function in adults with RA, spondyloarthritis (SpA), and psoriatic arthritis (PsA). Methods: The databases PubMed, Embase, CINAHL, and Cochrane Central Register of Controlled Trials (CENTRAL) were searched to identify relevant randomized controlled trials (RCTs). Screening, risk of bias assessment (using the RoB 2.0 tool), and data extraction were independently performed by 2 or more of the authors. Meta-analyses were conducted with a random-effects model. Results: Systematic review included 55 RCTs, and meta-analysis included 37 RCTs. Of the 55 studies included, 76%, 20%, and 4% were designed to investigate RA, SpA, and PsA, respectively. In the RA studies, effects of physical activity on QoL and function were found compared to the group of inactive controls; no effects were found compared to the group of active controls. In the SpA studies, the effects of physical activity on QoL were in favor of the control group. Effects of physical activity on function were found compared to the group of inactive controls and sustained in fatigue and pain when compared to the group of active controls. In the PsA studies, no effects on QoL were found, but effects on function were noted when compared to the group of inactive controls. The effect size was below 0.30 in the majority of the comparisons. Conclusion: Physical activity may improve QoL and self-reported function in individuals with RA, SpA, and PsA. However, larger trials are needed, especially in SpA and PsA.