The objective of this six weeks quasi-experimental study was to determine the effect of a structured physiotherapeutic treatment protocol on chronic low back pain sufferers' spinal flexibility. Ten (10) participants were purposively recruited and a one group pretest posttest design was adopted. A treatment plan involving the combination of fifteen minutes of Infrared Radiation, twenty minutes of Transcutaneous Electrical Nerve Stimulation, and ten minutes of Soft Tissue Massage was used to manage the condition. Each participant received treatment three times a week for a period of six weeks and all of them duly completed the study. Data were collected, organized, processed and analyzed descriptively and inferentially. Wilcoxon Signed-Rank test was used to test the null hypothesis at 0.05 level of significance. Statistical analysis revealed a significant improvement in the sufferers' spinal flexibilities, hence, it was concluded in this study that the above treatment protocol yielded a positive result in the management of chronic mechanical low back pain using spinal flexibility as the principal outcome measure.