Obesity is a major focus of researchers due to its increasing prevalence and relationship with other diseases, such as cancer and cardiovascular diseases. Probiotics are active microorganisms and have been proven to alleviate obesity by modulating the microbiota. In this study, we found that oral administration of Bifidobacterium adolescentis CCFM8630 to obese mice inhibited high-fat diet (HFD) -induced changes in body weight and adipose tissue and alleviated hepatic oxidative stress. Furthermore, B. adolescentis CCFM8630 treatment primarily affected the relative abundances of the phyla Proteobacteria and Actinobacteria, and thereby decreased the production of lipopolysaccharide (LPS) and the occurrence of LPSrelated diseases. A high fiber intake increased the abundance of Lactobacillus and the concentrations of shortchain fatty acids in obese mice, but these changes were reversed by B. adolescentis CCFM8630 treatment. In addition, targeted metabolomic analysis and microbiota relationship analysis revealed that B. adolescentis CCFM8630 treatment modified the microbiota of obese mice by promoting the conversion of tryptophan (Trp) to xanthurenic acid, kynurenic acid, tryptamine, indole-3-acetic acid, and indole-3-carboxaldehyde; facilitated the expression of interleukin-17A and the aryl hydrocarbon receptor to generate interleukin-22 in the colon; and upregulated the expression of tight junction proteins, thereby strengthening intestinal barriers. In summary, our findings suggest that the intake of B. adolescentis CCFM8630 may alleviate obesity by modulating the gut microbiota and related Trp metabolism.