Psoriasis is a chronic, inflammatory skin disease that has a profound psychological impact. Despite the pertinence of mental health difficulties to psoriasis, the literature is devoid of empirical support for the long-term beneficial effects of mindfulness-based interventions (MBIs). This study aimed to determine the comparative efficacy of mindfulness-based cognitive therapy (MBCT), mindfulness-based self-compassion therapy (MBSCT), and self-help MBSCT (MBSCT-SH) relative to treatment-as-usual (TAU) in improving the long-term psychological and physical outcomes of individuals with psoriasis. Ninety-four adults with mild to moderate psoriasis were randomly assigned to TAU (n = 22) or TAU combined with MBCT (n = 25), MBSCT (n = 25), or MBSCT-SH (n = 22). Participants completed assessments of psychological well-being, psoriasis symptom burden, and quality of life at pre- and post-treatment as well as 6- and 12-month follow-up. Although participants reported that the MBIs were beneficial, no statistically significant differences were found on psychological well-being, psoriasis symptom burden, or quality of life relative to TAU alone at post-treatment, 6- or 12-month follow-up. The development of our understanding of differences in the effects of MBIs for disparate disease groups is instrumental to realizing the therapeutic potential of MBIs.