Increasing evidence suggests that maternal diet during pregnancy modifies an offspring's microbiota composition and intestinal development in a long-term manner. However, the effects of maternal soluble fiber diet during pregnancy on growth traits and the developing intestine are still underexplored. Sows were allocated to either a control or 2.0% pregelatinized waxy maize starch plus guar gum (SF) dietary treatment during gestation. Growth performance, diarrhea incidence, gut microbiota composition and metabolism, and gut permeability and inflammation status of 14-day-old suckling piglets were analyzed. The maternal SF diet improved the growth rate and decreased the incidence of diarrhea in the piglets. Next-generation sequencing analysis revealed that the intestinal microbiota composition was altered by a maternal SF diet. The fecal and plasma levels of acetate and butyrate were also increased. Furthermore, a maternal SF diet reduced the levels of plasma zonulin and fecal lipocalin-2 but increased the plasma concentrations of interleukin 10 (IL-10) and transforming growth factor β (TGF-β). Additionally, the increased relative abundances of spp. in SF piglets were positively correlated with growth rate, while the decreased abundances of spp. were positively correlated with fecal lipocalin-2 levels. Our data reveal that a maternal SF diet during pregnancy has remarkable effects on an offspring's growth traits and intestinal permeability and inflammation, perhaps by modulating the composition and metabolism of gut microbiota. Although the direct effects of dietary soluble fiber on gut microbiota have been extensively studied, the more indirect effects of maternal nutrition solely during pregnancy on the development of the offspring's intestine are until now largely unexplored. Our data show that a maternal soluble fiber diet during pregnancy is independently associated with changes in the intestinal microbiota composition and metabolism of suckling piglets. These findings have direct implications for refining dietary recommendations in pregnancy. Moreover, a maternal soluble fiber diet reduces intestinal permeability and prevents intestinal inflammation and an excessive systemic immune response of suckling piglets. Therefore, the suckling piglets' resistance to disease was enhanced, diarrhea was reduced, and weight gain was raised. Additionally, the changes in gut microbiota in response to a maternal soluble fiber diet may also be directly correlated with the offspring's growth and gut development.