Background <p>Feeding practices are important in shaping children’s eating behaviors during early childhood. However, associations between caregiver concerns about preschoolers’ overweight/obesity and undereating and multiple feeding practices remain insufficiently understood. This study examined these associations and explored subgroup differences by parental and child characteristics in a large regional sample.</p> Methods <p>We analyzed data from 17,964 caregiver–child pairs from an online cross-sectional survey conducted in Chongqing, China, from September to October 2020, in the context of the COVID-19 pandemic. The sample included 17,342 parents and 622 grandparents of preschool-aged children. Caregivers reported concerns about child overweight/obesity and undereating, and six dimensions of feeding practices using five-point Likert scales. Multiple linear regression models with robust standard errors were used to examine the associations between caregivers’ concerns and feeding practices, adjusting for relevant covariates. Analyses were conducted separately for parents and grandparents, and interaction terms were used to examine subgroup differences by child and parental characteristics among parents.</p> Results <p>Among parents and grandparents, 63.8% and 69.9%, respectively, reported at least occasional concern about child overweight/obesity, and 76.1% and 82.8%, respectively, reported at least occasional concern about child undereating. Concern about overweight/obesity was mainly associated with restrictive feeding among both parents (<i>β</i> = 0.170, 95% CI 0.160–0.179) and grandparents (<i>β</i> = 0.098, 95% CI 0.042–0.155). Among parents, concern about undereating was mainly associated with pressure to eat (<i>β</i> = 0.204, 95% CI 0.195–0.212), restrictive feeding (<i>β</i> = 0.151, 95% CI 0.141–0.161) and instrumental feeding (<i>β</i> = 0.114, 95% CI 0.104–0.124), but negatively associated with mealtime rule-setting (<i>β</i> = −0.023, 95% CI − 0.032 to − 0.014). Among grandparents, concern about undereating was mainly associated with restrictive feeding (<i>β</i> = 0.246, 95% CI 0.189–0.302), instrumental feeding (<i>β</i> = 0.171, 95% CI 0.112–0.230), pressure to eat (<i>β</i> = 0.161, 95% CI 0.114–0.208). Among parents, these associations were generally consistent across subgroups, although with significant interactions observed for parental sex, education and child overweight/obesity status.</p> Conclusions <p>Caregivers’ concerns about preschoolers’ overweight or obesity and undereating were associated with a range of feeding practices. Notably, concerns about undereating were positively associated with coercive control practices, including restrictive feeding, pressure to eat, and instrumental feeding. These findings provide correlational evidence that may inform future family-based guidance to promote responsive and structured feeding strategies during early childhood.</p>