Collie-Preston MLA Mick Murray has formally announced his decision to retire at the March 2021 State Election.
Prior to entering politics, Mr Murray spent 23 years as an underground miner and 12 as a shire councillor.
He was first elected to parliament in 2001, before being re-elected in 2005, 2008, 2013, and 2017.
Due to electoral boundary changes, Mr Murray has represented more than 100 towns over the past two decades.
During his time as Collie-Preston MLA, he has helped to create the $20 million Collie Futures Fund and the $60m Collie Industry Attraction and Development Fund.
Mr Murray has established numerous projects for the town, including a $10m 'Adventure Trails' plan and a new Department of Fire and Emergency Services multi-purpose bushfire facility.
He also fought to deliver new facilities at Eaton Community College, upgrades to Eaton Primary School, and a new police station in Capel.
Mr Murray will continue on in his role as Minister for Sport and Recreation, Seniors and Ageing, and Volunteering up until the election.
"After what will be 20 years in parliament, the time has come to hand over the baton," he said.
"It is a privilege to have served so long as an MP and I can say with absolute certainty I left nothing in the locker.
"Over the course of five terms I've spent a lot of time working - both in the electorate and up in Perth - and I'm looking forward to spending more time with the family.
"Winning very tight elections in 2001, 2008 and 2013 were personal highlights but as a whole I'm proud of the fact I've remained true to my values, and always prioritised Collie and the South-West."
Premier Mark McGowan complimented Mr Murray on his hard work, loyalty, and dedication.
"Mick has made an important contribution during the first term of the McGowan Government," he said.
"He has performed his ministerial duties with professionalism and enthusiasm, and has worked extremely hard on behalf of his stakeholders.
"Mick is most recognised as a fierce, straight-talking advocate for the people of Collie-Preston, an electorate that includes the communities of Collie, Eaton, Capel, Dardanup, and Donnybrook.
"I thank Mick for his years of service to his electorate, and WA, and wish him and his family well for the next chapter of their lives."