When Geoff Gallop resigned due to illness in January 2006, Carpenter quickly emerged as the leading candidate to succeed him as premier, and gained crucial support from the Metal Workers Union.

[1] With the decisions of potential rivals Jim McGinty and Michelle Roberts to withdraw from the race, he was elected unopposed by the Labor caucus on 24 January.

After November 2006, Carpenter removed three cabinet ministers in four months for impropriety involving former WA Premier Brian Burke, exposed by the Corruption and Crime Commission.

Nevertheless, Carpenter's "no-nonsense" approach in dealing with this issue attracted a 60% public approval rating in opinion polls in late March 2007 (making him one of Australia's most popular state leaders, along with South Australian Premier Mike Rann).

The federal election came at a bad time for the Carpenter government; despite Labor's resounding victory nationwide, it actually lost two of its seats in Western Australia to the Liberals.

Under pressure to resign as Parliamentary Labor leader, Carpenter began negotiations with the National Party with a view to forming a minority government.

As a result, Alan Carpenter was succeeded by Colin Barnett as Western Australian Premier, and stepped down as Labor leader in favour of his deputy, Eric Ripper.

[9] Carpenter joined Australia's largest private sector employer Wesfarmers as executive general manager for corporate affairs in late 2009.