Objective: To investigate the effect of osteopathic visceral manipulation (OVM) on disability and pain intensity in individuals with functional constipation and chronic nonspecific low back pain. Methods: This study is a randomized controlled trial with a blinded assessor. Seventy-six volunteers with functional constipation and chronic nonspecific low back pain were randomized to two groups: OVM and sham OVM. The primary clinical outcome was pain intensity measured using a numeric rating scale (NRS) and disability measured using the Oswestry Disability Index (ODI). The secondary outcomes were electromyographic signals measured during the flexion-extension cycle, the finger-to-floor distance during complete flexion of the trunk and the Fear-Avoidance Beliefs Questionnaire (FABQ). All outcomes were determined after six weeks of treatment as well as three months after randomization. Results: The OVM group reported a reduction in pain intensity after six weeks of treatment and at the three-month evaluation (p < .0002) and the sham group reported a reduction in pain intensity after three-month evaluation (p < .007). For the ODI was also found in the OVM group six weeks after the end of treatment (treatment effect = -6.59, 95% CI: -12.01 to -1.17, p = .01) and at the three-month evaluation (treatment effect = -6.02, 95% CI: -11.55 to -0.49, p = .03). Significant differences were also found for paravertebral muscle activity during the dynamic phases (flexion and extension) six-week evaluations. Conclusions: The OVM group demonstrated a reduction in pain intensity and improvement in disability after six-weeks and three-month follow-up while the sham group reduction in pain three-month follow-up.