Matthew John Birney (born 10 June 1969) is an Australian politician. He was a Liberal member of the Western Australian Legislative Assembly from 2001 to 2008, serving as Leader of the Opposition from 2005 to 2006.
Birney was born in Sydney but comes from a family long established on the Western Australian goldfields, and has lived in the regional city of Kalgoorlie since childhood. His father, Jack Birney, was a Liberal member of the Australian House of Representatives from 1975 until his defeat in 1983.
The younger Birney was educated at North Kalgoorlie Primary and Eastern Goldfields Senior High School. He was a small business proprietor and a board member of the Kalgoorlie-Boulder Chamber of Commerce and Industry, before being elected to the Western Australian Legislative Assembly for the seat of Kalgoorlie in February 2001, defeating Labor incumbent Megan Anwyl.
The seat had long been a Labor stronghold; Labor had held it without interruption since 1923 and for all but seven years since its creation in 1901. However, Anwyl only led Birney by eight votes on the first count. Birney defeated Anwyl when the One Nation candidate Guy Hopkins's preferences flowed overwhelmingly to him. He was the first Liberal ever to win Kalgoorlie, and only the third non-Labor member in the seat's 100-year history. He was also the only Liberal challenger to unseat a Labor incumbent in an election which saw Labor elected to a strong majority government.