Brendan Johnston (born 25 November 1991) is an Australian professional racing cyclist, who primarily competes in gravel, road and mountain bike racing. He has won the national cross-country marathon championships six times, as well as three rounds of the UCI Gravel World Series and the Melbourne to Warrnambool Classic on the road.

Johnston started his career in junior mountain biking, where he saw success at the national level. However, his career was interrupted in 2009 when he was diagnosed with testicular cancer. He recovered and returned to competition in 2011.