Online grocery services are an emerging component of the food system with the potential to address disparities in access to healthy food. We assessed the barriers and facilitators of equitable access to healthy foods in the online grocery environment, and the psychosocial, purchasing, and dietary behaviors related to its use among low-income, diverse populations. Four electronic databases were searched to identify relevant literature; 16 studies were identified. Barriers to equitable access to healthy food included cost and limited availability of online grocery services in food deserts and rural areas. The expansion of online grocery services and the ability to use nutrition assistance benefits online were equity-promoting factors. Perceived low control over food selection was a psychosocial factor that discouraged online grocery use, whereas convenience and lower perceived stress were facilitators. Findings were mixed regarding healthfulness of foods purchased online. Although few studies assessed diet, healthy food consumption was associated with online grocery use.