Background &Objective: Low back pain is a frequent problem faced by the majority of people at some point in their lifetime. Exercise therapy has been advocated an effective treatment for chronic low back pain. However, there is lack of consensus on the best exercise treatment and numerous studies are underway. Conclusive studies are lacking especially in this part of the world. This study was designed to compare the effectiveness of specific stabilization exercises with routine physical therapy exercise provided in patients with nonspecific chronic mechanical low back pain. Methods: This is single blinded randomized control trial that was conducted at the department of physical therapy Orthopedic and Spine Institute, Johar Town, Lahore in which 120 subjects with nonspecific chronic low back pain participated. Subjects with the age between 20 to 60 years and primary complaint of chronic low back pain were recruited after giving an informed consent. Participants were randomly assigned to two treatment groups A & B which were treated with core stabilization exercise and routine physical therapy exercise respectively. TENS and ultrasound were given as therapeutic modalities to both treatment groups. Outcomes of the treatment were recorded using Visual Analogue Scale (VAS) pretreatment, at 2nd, 4th and 6th week post treatment. Results: The results of this study illustrate that clinical and therapeutic effects of core stabilization exercise program over the period of six weeks are more effective in terms of reduction in pain, compared to routine physical therapy exercise for similar duration. This study found significant reduction in pain across the two groups at 2nd, 4th and 6th week of treatment with p value less than 0.05. There was a mean reduction of 3.08 and 1.71 on VAS across the core stabilization group and routine physical therapy exercise group respectively. Conclusion: Core stabilization exercise is more effective than routine physical therapy exercise in terms of greater reduction in pain in patients with non-specific low back pain.