|Recently, microalgae are arousing considerable interest as a source of countless molecules with potential impacts in the nutraceutical and pharmaceutical fields. Haematococcus pluvialis, also named Haematococcus lacustris, is the largest producer of astaxanthin, a carotenoid exhibiting powerful health effects, including anti-lipogenic and anti-diabetic activities. This study was carried out to investigate the properties of two selected strains of H. pluvialis (FBR1 and FBR2) on lipid metabolism, lipolysis and adipogenesis using an in vitro obesity model. FBR1 and FBR2 showed no antiproliferative effect at the lowest concentration in 3T3-L1 adipocytes. Treatment with FBR2 extract reduced lipid deposition, detected via Oil Red O staining and the immunocontent of the adipogenic proteins PPARγ, ACLY and AMPK was revealed using Western blot analysis. Extracts from both strains induced lipolysis in vitro and reduced the secretion of interleukin-6 and tumor necrosis factor-α. Moreover, the FBR1 and FBR2 extracts improved mitochondrial function, reducing the levels of mitochondrial superoxide anion radical and increasing mitochondrial mass compared to untreated adipocytes. These findings suggest that FBR2 extract, more so than FBR1, may represent a promising strategy in overweight and obesity prevention and treatment.