(1) Background: Although manual therapy for pain relief has been used as an adjunct in treatments for chronic low back pain (CLBP), there is still the belief that a single session of myofascial release would be effective. This study aimed to investigate whether a single session of a specific technique reduces pain and disability. (2) Methods: This was a crossover clinical trial in which 41 participants over 18 years old with CLBP were randomly enrolled into 3 situations - experimental, placebo, control, in a balanced and cross-over manner. The subjects underwent a single session of myofascial release on thoracolumbar fascia and compare it with the control and placebo. Outcome were pain and functionality, evaluated using the numerical pain rating scale (NPRS), pressure pain threshold (PPT) and Oswestry (ODI). (3) Results: There was no effects between-, within-tests, and interaction for all the outcomes, i.e., NPRS (η 2 = 0.32, F = 0.48, p = 0.61), PPT (η2 = 0.73, F = 2.80, p = 0.06), ODI (η 2 = 0.02, F = 0.02, p = 0.97). (4) Conclusion: A single trial of thoracolumbar myofascial release technique was not enough to reduce pain and disability in subjects with CLBP.