Purpose: The objective of this study was to assess and evaluate the efficacy of posterior pelvic tilt exercises on pain reduction, functional disability, muscle strength, and lumbopelvic angle in patients with Chronic Low Back Pain (CLBP). These exercises were conducted on stable and unstable surfaces. Methods: This was a single-blinded randomized two-group pre-test and post-test experimental study. Men and women with CLBP, with an age between 18 and 50 years, were divided into two groups at random. Group A performed the exercises on a stable surface, and Group B performed the exercises on an unstable surface. The Numerical Pain Rating Scale (NPRS), Oswestry Disability Index (ODI) for functional disability, Flexi Ruler for measuring lumbar lordosis angle, and Surface Electromyography (SEMG) for Transverse Abdominis (TA) and Rectus Abdominis (RA) muscles were used for pre- and post-treatment analysis. Results: Significant improvements in SEMG activity of TA and RA muscles were observed in both intervention groups following conventional exercises ([Formula: see text] < 0.05). However, the unstable surface group had a higher increase in SEMG amplitude during Maximal Voluntary Isometric Contraction (MVIC) and the percentage of MVIC for the TA muscles. Conclusion: Posterior pelvic tilt exercises performed on stable and unstable surfaces effectively reduced pain, decreased the angle of lumbar lordosis, improved functional disability, and enhanced activity and strength of the pelvic muscles in patients with CLBP.