Exposure to environmental cues such as cold or nutritional imbalance requires white adipose tissue (WAT) to adapt its metabolism to ensure survival. Metabolic plasticity is prominently exemplified by the enhancement of mitochondrial biogenesis in WAT in response to cold exposure or β3-adrenergic stimulation. Here we show that these stimuli increase the levels of lysine-specific demethylase 1 (LSD1) in WAT of mice and that elevated LSD1 levels induce mitochondrial activity. Genome-wide binding and transcriptome analyses demonstrate that LSD1 directly stimulates the expression of genes involved in oxidative phosphorylation (OXPHOS) in cooperation with nuclear respiratory factor 1 (Nrf1). In transgenic (Tg) mice, increased levels of LSD1 promote in a cell-autonomous manner the formation of islets of metabolically active brown-like adipocytes in WAT. Notably, Tg mice show limited weight gain when fed a high-fat diet. Taken together, our data establish LSD1 as a key regulator of OXPHOS and metabolic adaptation in WAT.