Born in Belgrade, Principality of Serbia to a well-off family in a house located in Kralja Petra Street that has since been demolished (today, the National Bank of Serbia building is located in that spot).
Nušić enjoyed the benefits of a privileged upbringing for only a brief time. His father George Nusha (Đorđe Nuša) was a well known grain merchant of Cincar (Aromanian or Vlach) origin who lost his wealth shortly after his son's birth and was forced to move the family to Smederevo where young Branislav attended elementary school and first two grades of boarding school.
During his teens, he moved back to Belgrade where he graduated from boarding school. Upon turning 18 years of age, he legally changed his name to Branislav Nušić. In 1884, he graduated from the University of Belgrade's Law School. During his studies, he also spent a year in Graz, Austria-Hungary.