College students are experiencing heightened mental health difficulties, with problems intensifying during the COVID-19 pandemic. Mindfulness-Based Stress Reduction (MBSR) is a group intervention focused on cultivating mindfulness skills, with demonstrated efficacy in reducing psychopathology and bolstering mental health. This pilot randomized trial assessed the feasibility, engagement, and efficacy of an online adaptation of MBSR among healthy college students during the COVID-19 pandemic. Participants were randomly allocated to either an adapted MBSR group (n = 17) or a control group (n = 10). Participants completed mental health questionnaires prior to, and following the intervention. The intervention was demonstrated to be feasible and participants were engaged. Mindfulness-Based Stress Reduction participants reported greater increases over time in mindful self-compassion and observing mindfulness compared to control participants. Mindfulness-Based Stress Reduction participants demonstrated marginally greater overall mindfulness and well-being over time. This study identified small, clinically meaningful mental health effects of an online adaptation of MBSR among college students.