The lumbar-pelvic-hip complex, including the sacroiliac joint (SIJ), constitutes an interconnected anatomical unit. Dysfunctions within one region can often manifest as symptoms in others. Extensive research has established a significant association between lumbar prolapsed intervertebral disc (PIVD), a prevalent cause of low back pain, and SIJ abnormalities. Notably, up to 30.7% of individuals presenting with sciatica and low back pain exhibit concomitant SIJ dysfunction. While SIJ mobilization offers a promising therapeutic approach, further rigorous investigation is imperative to elucidate its efficacy for lumbar PIVD, particularly considering the potential risks associated with spinal and SIJ manipulation in this patient population. To find the efficacy of SIJ mobilization on pain, function and disability in patients with lumbar prolapse intervertebral disc. A total of 45 participants will be recruited based on predefined inclusion and exclusion criteria. A single-group, pre-test-post-test quasi-experimental design will be employed. Participants will receive SI joint mobilization utilizing a postero-anterior glide technique and lumbar extension, in conjunction with core muscle strengthening exercises. Pre- and post-intervention assessments will be conducted using the Visual Analogue Scale, Timed Up and Go Test, and the Oswestry Disability Index. Data Normality will be assessed using the Shapiro-Wilk test. For normally distributed data, paired t-tests will be used to analyze within-group differences. If the data is not normally distributed, the Wilcoxon Signed-Rank test will be used for within-group comparisons. This research aligns with a patient-centered approach, fostering a deeper understanding of the efficacy of SIJ mobilization on pain, function, and disability in patients with lumber PIVD.