Prompt Mental Health Care (PMHC, Norwegian adaptation of Improving Access to Psychological Therapies) is found successful in alleviating symptoms of anxiety and depression. Here, we investigate whether improvement is maintained over time. A randomized controlled trial was conducted in two PMHC sites from November 2015 to August 2017, randomly assigning 681 adults with anxiety and/or mild to moderate depression (70:30 ratio: PMHC n = 463, TAU n = 218). Main outcomes were recovery rates and changes in symptoms of depression and anxiety from baseline to 12 months. Secondary outcomes were functional status, health-related quality of life, mental wellbeing and work participation. At 12 months after baseline the reliable recovery rate was 59.4% in PMHC and 36.6% in TAU, giving a between-group effect size of 0.51 (95%CI: 0.26, 0.77, p < 0.001). Differences in symptom change gave between-group effect sizes of -0.67 (95%CI: -0.99, -0.36, p < 0.001) for depression and -0.58 (95%CI: -0.91, -0.26, p < 0.001) for anxiety. PMHC was also at 12 months found more effective in improving functional status, health-related quality of life and mental wellbeing, but not work participation. In sum, substantial treatment effects of PMHC remain at 12 months follow-up, although results should be interpreted with caution due to risk of attrition bias.Copyright © 2020 Elsevier Ltd. All rights reserved.