Background <p>Although the use of Online Grocery Shopping (OGS) is growing rapidly, the effect of OGS use on dietary intake remains unclear. The purpose of this study was to examine the differences in the mean values of dietary intake (food group intake, nutrient intake, and diet quality) between OGS users and non-users. Furthermore, to investigate the potential influence of age, analyses were conducted separately for working-age adults (&lt; 65 years) and older adults (≥ 65 years).</p> Methods <p>In this cross-sectional study, 2,851 residents of Ota Ward, Tokyo were surveyed using a validated questionnaire to quantitatively assess the food group intake, nutrient intake, and diet quality score of OGS user and non-user groups. Analysis of covariance was conducted to compare adjusted means of food group intake, nutrient intake, and diet quality score between OGS users and non-users after adjusting for covariates. Analysis was performed by age in working-age adult (&lt; 65y) and older (≥ 65 y) groups.</p> Results <p>OGS users in the working-age adult group had higher intakes of potatoes, vegetables, fruits, protein, fiber, and several vitamins and minerals and a higher diet quality score than OGS non-users. In contrast, a relationship between OGS use and dietary intake was not apparent in the older group.</p> Conclusions <p>OGS use was associated with a better dietary intake among the working-age adult group. Potential benefits of OGS use may not be fully realized among older populations, possibly due to differences in the rationale for OGS use and in digital literacy. Establishing a support system that enables older people to appropriately adopt and effectively utilize OGS may have the potential to serve as a tool that contributes to better food intake and diet quality among older adults.</p>