Postbiotics have recently garnered substantial research attention, especially in obesity research. In this study, upon comparing the proliferative effects of three food-derived media-skim milk, soy milk, and almond milk-on Lactiplantibacillus plantarum J26 (L. plantarum J26), skim milk was found to be the most effective. The metabolomic analysis further unveiled that the metabolites produced by the strain cultured in skim milk influenced the greatest number of lipid metabolism-associated pathways. Additionally, to better preserve heat-sensitive substances, ultrasound and pasteurization were combined and used here for inactivation. L. plantarum J26 postbiotics, prepared through pasteurization combined with 400 W ultrasound treatment for 30 min, exhibited the most effectiveness at inhibiting cellular triglyceride accumulation, reducing its level to 0.99 mg per 104 CFU. The prepared postbiotics significantly reduced the increase in multiple indicators, including body weight, blood lipids, and adipokines in obese mice (p < 0.05). Following treatment, liver tissue damage as well as white and brown adipose tissue damage were also markedly improved in obese mice. According to gut microbiota sequencing, the postbiotic intervention increased Lactobacillus and Bifidobacterium abundances but reduced the abundances of obesity-associated Faecalibacterium and Erysipelotrichaceae. Additionally, the postbiotics elevated the acetate, propionate, and butyrate levels by 14.95%, 23.89%, and 8.31%, respectively. High postbiotic doses significantly upregulated the expression of GPR41/GPR43, short-chain fatty acid (SCFA) receptor genes, in the liver and adipose tissues (p < 0.05), thus correcting the obesity-induced anomalies in the SCFAs-GPR41/GPR43 signaling pathway. This research offers compelling evidence supporting the use of edible postbiotics in targeted obesity regulation.