Mark McGowan's cabinet has been changed just days after being sworn in, with Peter Tinley losing the mines and petroleum portfolio over a potential or perceived conflict of interest.
WA's new Labor government says it emerged at the first cabinet meeting on Monday that a member of Mr Tinley's family worked in the oil and gas industry, so former energy spokesman Bill Johnston has taken on mines and petroleum.
Mr Tinley will assume housing from Bahasa-speaking Mr Johnston, who is minister for the Labor-created Asian engagement portfolio.
"This is a responsible change to state cabinet to ensure ministers can do their job without any conflicts, potential or perceived," Mr McGowan said in a statement.
"Although the conflict could have been managed in an appropriate manner, I have made the decision to put the issue beyond any doubt."
Also on Tuesday, Labor came under fire from WA Liberals deputy leader Liza Harvey for adding a parliamentary secretary of the cabinet, Amber Jade-Sanderson, to its 17-member ministry.
"The first thing he's done is created an additional high-paid job for one of his people," Ms Harvey told reporters.
"He's effectively created a ministry of 18."