Abstract Spa therapy is considered an add-on treatment for psoriasis, but without any objective evaluation in the absence of randomized trials. This multicenter, open-label, randomized trial compared immediate spa therapy versus a control group having usual treatments until study assessments at 4.5 months. Spa therapy was proposed in five French spa resorts with standardized programs. Inclusion criteria were adults with plaque psoriasis, Dermatology Life Quality Index (DLQI) > 10, and stable medical treatment in the last 6 months. The main objective was DLQI ≤ 10 at 4.5 months after inclusion. VQ-Dermato and EQ5D-3L also assessed quality of life (QoL), Perceived Stress Scale (PSS) stress, and visual analogue scales (VAS) pain and pruritus. Between January 2015 and November 2018, 128 patients were randomized to either immediate spa therapy (64) (within 34 days, median) or usual treatments (61) until assessment at 4.5 months. Most were first-time spa users (71.2%). Mean DLQI and Psoriasis Area and Severity Index at inclusion were 16.7 and 10.5, respectively. Immediate spa therapy patients achieved the primary objective for 66.1% [95% CI 52.6% > 77.9%] vs 41.4% [95% CI 28.6% > 55.1%] control group patients ( p = 0.007). VQ-Dermato scores and pruritus VAS significantly improved. Outcomes at 12-month follow-up of the immediate spa therapy group showed persistent improvement of DLQI, VQ-Dermato, and pruritus. This randomized controlled trial demonstrated that a cure of spa therapy improves QoL and alleviates certain symptoms of psoriasis, in short and long terms. This justifies its integration in the therapeutic strategies for psoriasis. Trial registration number: ClinicalTrials.gov Identifier: NCT02098213.