The dry period is a critical stage for fetal development, during which maternal nutritional and metabolic status are strongly associated with postnatal growth and organ development in calves. Among metabolic indicators, elevated maternal serum β-hydroxybutyrate (BHB) concentrations during this period have attracted increasing attention; however, their relationships with offspring rumen development remain poorly defined. This study aimed to investigate the impact of high maternal BHB concentrations during the dry period on rumen development in neonatal and one-month-old calves. Forty-eight Holstein cows with similar body weight, parity, and expected calving date were monitored throughout the dry period. Based on serum BHB concentrations measured at wk -7, -5, -3, and -1 during the dry period, cows were classified into a low-BHB group (CON; 0.23 ± 0.02 mM; n = 24) or a high-BHB group (MB; 0.69 ± 0.03 mM; n = 24). Rumen tissues were collected from calves at birth and at one month of age to assess morphological development and inflammatory responses. Maternal BHB concentrations did not affect calf birth weight; however, calves from MB cows showed association with increased rumen mass but reduced papilla length and width, indicating association with impaired structural development. Rumen epithelial integrity related markers were altered in the MB group, as evidenced by downregulation of the tight junction protein Claudin1 and upregulation of inflammatory cytokines. Furthermore, expression of peroxisome proliferator-activated receptor (PPAR) γ was markedly reduced in MB calves, consistent with morphological alterations and inflammation. In conclusion, high maternal BHB concentrations during the dry period may impair rumen development in offspring calves potentially by influencing pathways related to epithelial barrier related markers, altering metabolic gene regulation, and promoting PPARγ mediated inflammatory signaling. These findings emphasize the importance of nutritional strategies during the dry period to mitigate maternal metabolic disturbances and support optimal rumen epithelial development and function in offspring calves.