Buprenorphine is an important medication for treating opioid use disorder, but medication adherence and treatment retention are key issues that can limit its impact, especially when patients have concurrent stimulant use. Contingency management is efficacious in promoting medication adherence and drug abstinence. Delivering contingency management via smartphones addresses practical barriers to its adoption and improves patient access. A single-group (n = 20) nonexperimental study was conducted to evaluate the feasibility of smartphone-based contingency management to promote adherence to buprenorphine treatment in people with opioid use disorder. Participants were recruited from outpatient treatment clinics. Over 12 weeks participants had access to a smartphone app that provided contingency management supported with peer recovery coaching. Adherence was confirmed daily either by GPS monitoring of clinic medication visits or self-recorded video, and salivary toxicology was conducted weekly. The overall rate of confirmed buprenorphine adherence was 76%, and visual inspection of individual participant outcomes shows consistent medication use for a large majority of participants. All participants were able to successfully use all app features and spend earnings. Participants rated the app and intervention highly on measures of likability, ease of use, and helpfulness. All participants (100%) were retained in buprenorphine treatment throughout the study period. Direct methods for confirming adherence appear superior to confirmation via salivary toxicology. This study shows that smartphone-based contingency management is a feasible means of promoting buprenorphine adherence. The potential efficacy of smartphone-based contingency management as a means of promoting buprenorphine adherence warrants evaluation in a randomized controlled trial.