BackgroundGlobally, most individuals who are susceptible to depression do not receive adequate or timely treatment. Unguided computerized cognitive behavioral therapy (cCBT) has the potential to bridge this treatment gap. However, the real-world effectiveness of unguided cCBT interventions, particularly in low- and middle-income countries (LMICs), remains inconclusive.ObjectiveIn this study, we aimed to report the design and development of a new unguided cCBT–based multicomponent intervention, TreadWill, and its pragmatic evaluation. TreadWill was designed to be fully automated, engaging, easy to use, and accessible to LMICs.MethodsTo evaluate the effectiveness of TreadWill and the engagement level, we performed a double-blind, fully remote, and randomized controlled trial with 598 participants in India and analyzed the data using a completer’s analysis.ResultsThe users who completed at least half of the modules in TreadWill showed significant reduction in depression-related (P=.04) and anxiety-related (P=.02) symptoms compared with the waitlist control. Compared with a plain-text version with the same therapeutic content, the full-featured version of TreadWill showed significantly higher engagement (P=.01).ConclusionsOur study provides a new resource and evidence for the use of unguided cCBT as a scalable intervention in LMICs.Trial RegistrationClinicalTrials.gov NCT03445598; https://clinicaltrials.gov/ct2/show/NCT03445598