In this small, single-center randomized controlled trial of 60 patients with plaque psoriasis, sliding cupping therapy performed three times weekly for 8 weeks produced improvements in disease severity comparable to narrowband ultraviolet B (NBUVB) phototherapy. Both groups showed significant reductions in Psoriasis Area and Severity Index (PASI), body surface area involvement, Physician’s Global Assessment scores, and itch severity over time, with no statistically significant differences between treatments at any time point. At week 8, mean PASI reductions were 62.4% with cupping and 66.9% with NBUVB, and response rates (≥30% PASI improvement) were 69% and 79%, respectively. Quality of life (DLQI) improved in both groups, while patient-reported quality of life did not change significantly. Adverse events were mild and infrequent, with no serious events reported.