Objective First, to evaluate the outcome of 2 transdiagnostic day treatment programs. A 20‐week psychotherapeutic day treatment (PDT) and an activating day treatment (ADT) program delivered in blocks of 4 weeks with a maximum of 24 weeks with respect to depression, anxiety, and hypochondriasis. Second, to explore the impact of cognitive impairment and personality pathology on treatment outcome. Methods The course of depression (Inventory of Depressive Symptoms), anxiety (Geriatric Anxiety Inventory), and hypochondriasis (Whitley Index) were evaluated by linear mixed models adjusted for age, sex, level of education, and alcohol usage among 49 patients (mean age 65 years, 67% females) receiving PDT and among 61 patients (mean age 67.1, 61% females) receiving ADT. Pre‐post effect‐sizes were expressed as Cohen's d. Subsequently, cognitive impairment (no, suspected, established) and personality pathology (DSM‐IV criteria as well as the Big Five personality traits) were examined as potential moderators of treatment outcome. Results Among patients receiving PDT, large improvements were found for depression (d = 1.1) and anxiety (d = 1.2) but not for hypochondriasis (d = 0.0). Patients receiving ADT showed moderate treatment effects for depression (d = 0.6), anxiety (d = 0.6), as well as hypochondriasis (d = 0.6). Personality pathology moderates treatment outcome of neither PDT nor ADT. Cognitive impairment negatively interfered with the course of depressive symptoms among patients receiving PDT. Conclusions Transdiagnostic day treatment is promising for older adults with affective disorders with high feasibility.