IntroductionPerinatal anxiety (PNA) is a major public health concern.MethodsA hybrid effectiveness-implementation trial was conducted in two antenatal clinics in Hefei, China, to assess the effectiveness and cost-effectiveness of application-based tiered care (Mom’s Good Mood, MGM) in treating PNA and to understand how well it fits into routine practices. Pregnant women who scored at least 5 points on the 7-Item Generalised Anxiety Disorder Scale (GAD-7) scale were successively assigned to the control group or the intervention group, which were given the usual care and MGM on usual care, respectively. At 6 months post partum, anxiety, depression and life satisfaction were assessed. Intention-to-treat analysis and the Reach, Effectiveness, Adoption, Implementation and Maintenance framework were adopted.ResultsA total of 214 women were assigned to the control group and 341 to the intervention group. The mean changes in GAD-7 scores (Least-squares means, LSM, −1.42, 95% CI −2.18 to −0.66) and the risk of anxiety (adjusted odds ratio, aOR 0.30, 95% CI 0.18 to 0.51) were decreased, and the anxiety remission rate (aOR 2.72, 95% CI 1.69 to 4.40) were improved in the intervention group. Similar findings were observed regarding the change in Edinburgh Postnatal Depression Scale scores (LS −1.92, 95% CI −2.85 to −0.99), depression remission rate (aOR 2.24, 95% CI 1.39 to 3.63) and the risk of depression (aOR 0.57, 95% CI 0.33 to 0.98). MGM only costs ¥1.88 (US$0.27) per pregnant woman to boost the postpartum anxiety remission rate by 1% and was revealed to have a high reach rate of 78.3%, an adoption rate of 51.3%–80.8%.ConclusionMGM is a cost-effective and accessible tool in coping with PNA.Trial registration numberChiCTR2100053419.