The aim of this study was to examine the potential moderating effect of baseline emotion regulation skills¿cognitive reappraisal and expressive suppression¿on the relation- ship between treatment allocation and treatment outcomes in primary care patients with emotional symptoms. A total of 631 participants completed scales to evaluate emotion regulation, anxiety, depression, functioning, and quality of life (QOL). The moderation analysis was carried out using the SPSS PROCESS macro, version 3.5. Expressive suppression was a significant moderator in the relationship between treatment allocation and treatment outcomes in terms of symptoms of anxiety (b = 0.530, p = .026), depression (b = 0.812, p = .004), and QOL (b = 0.156, p = .048). Cognitive reappraisal acted as a moderator only in terms of QOL (b = 0.217, p = .028). The findings of this study show that participants with higher scores of expres- sive suppression benefited more from the addition of trans- diagnostic cognitive-behavioral therapy to treatment as usual (TAU) in terms of anxiety and depressive symptoms, and QOL. Individuals with higher levels of cognitive reappraisal obtained a greater benefit in terms of QOL from the addition of psychological treatment to TAU. These results underscore the relevant role that emotion regulation skills play in the outcomes of psychological therapy for emotional symptoms.