Long-term stored oolong tea has recently attracted considerable attention concerning its salutary effect. In this study, the anti-obesity effect of different years' oolong tea on high-fat diet-fed mice was compared. Wuyi rock tea of 2001, 2011, and 2020 were chosen to be the representative samples of oolong tea. The results showed that eight-week administration of 2001 Wuyi rock tea (WRT01), 2011 Wuyi rock tea (WRT11), and 2020 Wuyi rock tea (WRT20) extracts (400 mg per kg per d) significantly decreased the body weight and attenuated the obesity in high-fat diet-fed mice. 2001 and 2011 Wuyi rock teas reduced obesity mainly through regulating lipid metabolism and activating the AMPK/SREBP-1 pathway, downregulating the expression of SREBP-1, FAS, and ACC and upregulating CPT-1a expression; while the 2011 and 2020 Wuyi rock teas by moderating the gut microbiota dysbiosis, reshaping the gut microbiota, and promoting the growth of beneficial bacteria, especially Akkermansia. 2011 Wuyi rock tea was proven to be more effective in reducing body weight gain and liver oxidative stress than the others. Collectively, all three Wuyi rock teas of different years alleviated high-fat diet-induced obesity by regulating lipid metabolism and modulating gut microbiota, whereas the emphasis of their internal mechanism is different with different storage ages.