The Canadian stars share a common family connection dating back 400 years from the earliest settlers in Quebec and are 11th cousins once removed.
Justin is also related to fellow Canadians Avril Lavigne and Celine Dion, thanks to common relatives Mathurin Roy and Marguerite Bire with Avril and Jacques Vezina and Marie Boisdon with Dion, according to Ancestry.com.
Genealogist Lesley Anderson admits such discoveries are ''rare'' and is shocked to discover how many Canadian entertainers are related.
She said: ''Discoveries like this are rare, so the fact that some of Canada's top entertainment industry stars are all related is especially fascinating.
''There's something special about discovering a shared connection, and to be able to go so far back in history to do so is one of the most satisfying aspects of family history research.''
Justin and Avril have met on several occasions, including at the BRIT Awards in London in 2011, although it is not known if they knew about the connection at the time.
Quebec was populated by French settlers from the early 1500s, before being conquered by the British in the mid 18th century.