Objective The aim of this study was to investigate the effects of abdominal massage on the severity of constipation, bowel function, and quality of life (QoL) in patients with functional chronic constipation in a randomized placebo-controlled design. Methods Seventy-four patients diagnosed with functional constipation according to the Rome IV diagnostic criteria were included. Patients were randomly assigned to the intervention group (abdominal massage plus lifestyle advice) or the control group (placebo therapeutic ultrasound plus lifestyle advice). Abdominal massage or placebo ultrasound was applied for 4 weeks. The primary outcome measure was the Constipation Severity Instrument score. Bowel diary data and the Patient Assessment of Constipation Quality of Life Questionnaire score were used as secondary outcome measures. Differences in outcome measures within and between groups were analyzed by repeated-measures analysis of variance. Results Although constipation severity, bowel function indicators (defecation frequency and duration and stool consistency), and QoL were found to improve significantly over time in both groups, improvements in both primary and secondary outcomes were much more significant in the abdominal massage group. In addition, group x time interaction effects were found to be significant for constipation severity, bowel function findings, and QoL. There were approximately 70% and 28% reductions in constipation severity, 56% and 38% improvement rates in QoL, and 70% and 43% increases in defecation frequency in the intervention and placebo groups, respectively. Conclusion Abdominal massage should be one of the first-line conservative approaches in the management of functional chronic constipation. Further randomized placebo-controlled studies with long-term follow-up are needed. Impact For functional constipation, which is a common gastrointestinal problem, abdominal massage should be considered as an option in first-line therapy because of its effect beyond the placebo effect. Lay Summary If you have functional constipation, your physical therapist may be able to provide abdominal massage to help reduce your symptoms.