He first shot to fame the age of 19 in 2001, when he finished runner-up in the inaugural season of the reality TV series Big Brother.
McDonough spent much of his childhood living in Singapore, where his parents were working, where he was educated at Tanglin Trust School and the United World College of South East Asia.
Blair and his brothers Wade, Gavin and Ryan were members of the band Snubrocket (later renamed Fifth Avenue), which was one of 30 that appeared in the music video clip for TISM's song "Thunderbirds Are Coming Out" in 1998.
A few months after Big Brother concluded, McDonough was cast in the long-running Australian soap opera Neighbours, in the role of Stuart Parker.
In January 2007, he appeared in BBC Two's Safari School, in which eight celebrities took part in a four-week ranger training course in the Shamwari Game Reserve in South Africa.
[1] In 2009, McDonough appeared in the Australian Nine Network drama Sea Patrol in the semi-regular cast as the character Matt Robsenn.
McDonough signed on as a celebrity dancer in the 2010 season of Australia's Dancing with the Stars, but was the second person to be eliminated from the competition after receiving the fewest public votes on 11 July 2010.