Brown adipose tissue (BAT) plays a key role in regulating glucose homeostasis and insulin sensitivity. This study demonstrates that transplanting BAT into mice significantly improves glucose tolerance, insulin sensitivity, and metabolic health. Transplanted BAT increased glucose uptake in endogenous BAT, white adipose tissue (WAT), and heart, but not in skeletal muscle. The effects were dependent on BAT-derived interleukin-6 (IL-6), as BAT from IL-6 knockout mice failed to improve glucose homeostasis. These findings suggest that BAT functions as an endocrine organ that regulates glucose metabolism through paracrine and endocrine mechanisms. BAT transplantation also improved metabolic parameters in mice fed a high-fat diet, reducing body weight and improving glucose tolerance. The beneficial effects were associated with increased levels of norepinephrine, FGF21, and IL-6. BAT-derived IL-6 is essential for the metabolic improvements observed. The transplanted BAT retained brown adipose tissue characteristics, including thermogenic function and glucose uptake. These results highlight the potential of BAT transplantation as a therapeutic strategy for obesity and metabolic diseases.Brown adipose tissue (BAT) plays a key role in regulating glucose homeostasis and insulin sensitivity. This study demonstrates that transplanting BAT into mice significantly improves glucose tolerance, insulin sensitivity, and metabolic health. Transplanted BAT increased glucose uptake in endogenous BAT, white adipose tissue (WAT), and heart, but not in skeletal muscle. The effects were dependent on BAT-derived interleukin-6 (IL-6), as BAT from IL-6 knockout mice failed to improve glucose homeostasis. These findings suggest that BAT functions as an endocrine organ that regulates glucose metabolism through paracrine and endocrine mechanisms. BAT transplantation also improved metabolic parameters in mice fed a high-fat diet, reducing body weight and improving glucose tolerance. The beneficial effects were associated with increased levels of norepinephrine, FGF21, and IL-6. BAT-derived IL-6 is essential for the metabolic improvements observed. The transplanted BAT retained brown adipose tissue characteristics, including thermogenic function and glucose uptake. These results highlight the potential of BAT transplantation as a therapeutic strategy for obesity and metabolic diseases.