Especially for adult patients with anorexia nervosa (AN), treatment response is generally low to moderate. The present study aimed to evaluate the efficacy of cognitive remediation therapy (CRT) as adjunctive treatment for AN regarding clinical and cognitive outcomes. In this randomized controlled superiority trial, 167 adult and adolescent (≥17 years) patients with AN were randomly allocated (1:1) to 10 weekly sessions of group therapy of either CRT (n = 82) or art therapy (ART; n = 85) as an adjunct to inpatient treatment-as-usual (TAU). Outcomes were assessed at baseline, end-of-treatment (10 weeks), and 6-month follow-up. Change in body mass index (BMI), eating disorder psychopathology, and health-related quality of life (QoL) from baseline to 6-month follow-up served as primary outcomes. Improvements in motivation to change and several indices of set-shifting and central coherence between baseline and end-of-treatment and between baseline and 6-month follow-up served as secondary outcomes. Analysis was by intention to treat. Treatment groups did not differ regarding change in BMI, eating disorder psychopathology, and health-related QoL from baseline to 6-month follow-up. Likewise, groups neither differed regarding improvements in these outcomes between baseline and end-of-treatment nor in motivation to change, set-shifting, and central coherence at any time, except for greater short-term improvements in one measure of set-shifting in the CRT group. CRT as an adjunct to inpatient TAU for AN was not efficacious in improving clinical and cognitive outcomes. The results do not support routine employment of CRT in inpatient treatment for AN. (PsycInfo Database Record (c) 2021 APA, all rights reserved).