We assessed if supplementation of an obese-inducing diet with yellow pea fibre throughout pre-pregnancy (PP), gestation, and lactation could influence maternal gut microbiome composition and improve metabolic health and liver steatosis in newly weaned rat male and female offspring. Forty female Sprague-Dawley rats were fed a low (CON) or high (HC) calorie diet for a 6-week PP period. At the end of PP, HC animals were randomly assigned to either remain on the HC diet or the HC diet with yellow pea fibre (HC + FBR) for an additional 4-weeks prior to mating and throughout gestation and lactation. At the end of lactation, caecal microbiome profile was evaluated in mothers with shotgun metagenomic sequencing, and newly weaned male and female pups were assessed for serum biochemistry and hepatic fat outcomes. Maternal obesity reduced the beta-diversity of the maternal microbiome and lowered total caecal short-chain fatty acid (SCFA) concentration. HC + FBR consumption increased caecal SCFA concentration and differentially altered the maternal caecal microbiome profile of several species that have been linked with hepatic steatosis including Bifidobacterium pseudolongum, Porphyromonas gingivalis, and several Provetella species. Newly weaned offspring from HC mothers exhibited hepatic steatosis; however, male and female pups from HC + FBR mothers demonstrated normalised liver lipid concentrations (cholesterol and triglyceride) and an increase in caecal acetate and propionate concentrations. Findings suggest that maternal obesity enhances the risk of liver steatosis in offspring and that maternal dietary fibre supplementation may have a protective influence that is partly mediated through changes in the caecal microbiome profile and activity.