Best Actor in a Supporting Role is a British Academy Film Award presented annually by the British Academy of Film and Television Arts (BAFTA) to recognize an actor who has delivered an outstanding supporting performance in a film.

The British Academy Film Awards, more commonly known as the BAFTA Awards, is an annual award show hosted by the British Academy of Film and Television Arts (BAFTA) to honour the best British and international contributions to film. The ceremonies were initially held at the flagship Odeon Cinema in Leicester Square in London, before being held at the Royal Opera House from 2007 to 2016. From 2017 to 2022, the ceremony was held at the Royal Albert Hall in London before moving to the Royal Festival Hall for the 2023 ceremony. The statue awarded to recipients depicts a theatrical mask.