Autistic adults face heightened risk of psychiatric disorders, with depression occurrence estimated at quadruple the rate of the general population. Mindfulness Based Stress Reduction (MBSR), an intensive 8-week in-person intervention, reduces depressive symptoms in adults with autism spectrum disorder (ASD). However, access to these programs is restricted due to financial, geographic, and scheduling limitations. Additionally, lapses in practice post-intervention cause these effects to be short-lived. This study examines antidepressant effects of an 8-week app-delivered mindfulness meditation intervention using Ten Percent Happier in adults with ASD and explores whether anchoring meditation practice to a preexisting behavior will improve therapy compliance and depression-related efficacy. Ninety-seven participants were randomly assigned to either App Only (n=30), App + Habit training (n=27) or Waitlist Control (n=40). App Only and App + Habit groups were requested to meditate a minimum of 10 minutes per day, 5 days per week for 8 consecutive weeks using the mobile application. The App + Habit group received additional instruction to anchor leaving the bathroom each morning with meditation; The App Only group was only provided with education on habit formation. Participants completed the Beck Depression Inventory-II (BDI-II) at pre- and post-intervention. All groups received weekly ecological momentary assessments (EMAs) to assess frequency and length of practice. The App + Habit group was additionally assessed for cue-initiated meditation frequency. Data were analyzed using repeated measures analysis of variance (ANOVA). Pre-to-post changes on BDI-II scores indicated a group by time interaction (p=0.04) and a main effect of time (p <0.001). Post-hoc analysis revealed the App + Habit group exclusively showed significant decline in depressive symptoms (p<0.001). The App + Habit group showed greater number of days meditated, average minutes per day of meditating, and continuation of meditation practice 8-weeks after the intervention period, compared to the App Only group. Findings support app-delivered mindfulness interventions as an accessible and cost-effective alternative to traditional in-person mindfulness training for Autistic adults. However, results suggest app-based mindfulness tools may only be effective when delivered with specific habit formation instruction. Additionally, habit formation instruction led to greater adherence to meditation practice after the study period ended.