Sixty adults with clinically diagnosed frozen shoulder were randomized to receive intra-articular lidocaine plus active manual therapy (scapular mobilization and posterior capsular stretching; n = 30) or intra-articular lidocaine plus sham manual therapy (light touch/simulated mobilization; n = 30), in addition to a standardized physiotherapy and progressive resistance exercise program delivered four times per week for four weeks. The primary outcome was shoulder pain intensity measured on a 10-cm visual analogue scale (VAS). Secondary outcomes included shoulder range of motion (abduction and lateral rotation), functional disability (QuickDASH), coracohumeral ligament (CHL) thickness on MRI, kinesiophobia (TSK-AV), depression (HADS), and health-related quality of life (EQ-5D), assessed at baseline, 4 weeks, 8 weeks, and 6 months. Overall, the results of the study revealed that the active manual therapy group had significantly greater reductions in pain (between-group VAS differences 2.4–3.0 points), larger improvements in CHL thickness, disability, kinesiophobia, depression, and quality of life across all follow-up points (all p ≤ 0.001, large effect sizes) compared with the sham group. These findings suggest that combining targeted manual therapy with lidocaine injection and structured exercise provides clinically important added benefit over lidocaine plus non-therapeutic contact alone in the management of frozen shoulder.