Mindful walking has emerged as a potential intervention strategy to improve mental health and promote well-being in adult and clinical populations. This strategy has not been implemented specifically with older adults to date. This study evaluated the feasibility, acceptability, sustainability, and preliminary efficacy of a mindful walking program for reducing negative affect in older adults. Community-dwelling older adults (n = 29) completed a 1-month, outdoor mindful walking program distributed across eight 30-min sessions. Responses from postprogram and follow-up questionnaires revealed that mindful walking was well-accepted, highly valued, and maintained after the program ended. Analysis from the pre- and postwalk surveys also suggested the preliminary efficacy of a mindful walking program for reducing negative affect. Positive results identified in the current feasibility study indicate readiness for randomized controlled trials to further examine the efficacy and effectiveness of a mindful walking intervention for promoting health and well-being in older populations.