Cell depolarization is a pivotal event in the regulation of aldosterone secretion from adrenal zona glomerulosa cells by angiotensin II and high plasma K⁺. The 2-pore domain potassium channels TASK3, TASK1 and TREK1 are important for the control of the membrane voltage of these cells. This study was aimed at investigating the particular contribution of TASK3 potassium channels to the regulation of aldosterone production. TASK3-specific immunofluorescence was detected in zona glomerulosa cells and to a lesser extent in zona fasciculata cells. The expression and localization of TASK3 was sex-dependent with higher levels in male mice. The deletion of TASK3 gene caused an impairment of the regulation of aldosterone secretion in vivo. In ex vivo experiments using perifused adrenal gland tissue, small changes in the K⁺ dependence of aldosterone secretion were observed. Patch clamp experiments on adrenocortical primary cells of TASK3 knockout mice showed a depolarized resting membrane voltage compared to wildtype cells. Similarly, in adrenal gland slices from TASK3 knockout animals the physiological regulation of the cytosolic Ca²⁺ activity appeared to be disturbed. These data provide new insights into the role of TASK3 channels for the control of membrane voltage and aldosterone secretion and could have implications for human disorders linked to pathological production of this hormone.