The beta-3 adrenergic receptor (β3-AR) is by far the least studied isotype of the beta-adrenergic sub-family. Despite its study being long hampered by the lack of suitable animal and cellular models and inter-species differences, a substantial body of literature on the subject has built up in the last three decades and the physiology of β3-AR is unraveling quickly. As will become evident in this work, β3-AR is emerging as an appealing target for novel pharmacological approaches in several clinical areas involving metabolic, cardiovascular, urinary, and ocular disease. In this review, we will discuss the most recent advances regarding β3-AR signaling and function and summarize how these findings translate, or may do so, into current clinical practice highlighting β3-AR’s great potential as a novel therapeutic target in a wide range of human conditions.