Background: MASLD is closely linked to gut–liver axis dysfunction, including altered microbial activity, disturbed bile acid metabolism, and hepatic lipid accumulation. Raspberry polyphenols may help counteract these dis- turbances, whereas fructooligosaccharides (FOS) may enhance their microbial transformation and biological activity. Methods and results: Male Wistar rats were fed for 12 weeks with a control diet, a high-fat low-fiber diet (HF), or HF diets supplemented with raspberry polyphenols alone (HF + PP) or combined with FOS (HF + PP + FOS). Compared with HF feeding alone, the combined treatment produced the most favorable response, including lower hepatic triglyceride and cholesterol accumulation, improved plasma lipid indices, higher hepatic and plasma levels of polyphenol-derived metabolites, reduced hepatic Ahr/AHR expression, increased Cyp8b1/ CYP8B1 expression, enhanced short-chain fatty acid production, altered cecal bile acid profile, lower activity of selected bacterial enzymes, and a distinct shift in cecal microbiota composition. Conclusion: Combined supplementation with raspberry polyphenols and fructooligosaccharides partly alleviated selected metabolic and intestinal disturbances induced by a high-fat, low-fiber diet. The findings may support the involvement of the gut–liver axis and suggest that FOS may strengthen the functional effects of raspberry polyphenols by promoting microbial fermentation and increasing the formation and availability of smaller bioactive metabolites. Overall, the combination of a polyphenol-rich raspberry preparation with a microbiota- targeting prebiotic may represent a nutritionally relevant strategy for supporting metabolic homeostasis under MASLD-like conditions