Speaker of the House of Representatives Tony Smith will step down from the role next month.
Mr Smith previously announced he would resign from parliament at the next election, but on Thursday said he would quit as Speaker on November 22.
He will spend his final months in politics as a Liberal backbench MP.
A new Speaker will be elected on November 23.
"Being your Speaker has been an incredible honour, I love the job and obviously what I'm saying now is a very difficult decision," Mr Smith told parliament.
"I want to spend my remaining time in the house working exclusively for the people of Casey."
Mr Smith has been Speaker for more than six years.
He said he announced his decision early to allow for the election of a new Speaker.
"It's not because I'm tired of the job, I doubt I would ever tire of it," Mr Smith said.
"Let me say clearly if there is anyone within or outside this house who thinks my decision is the result of some disquiet with the government, you are wrong."
Prime Minister Scott Morrison led tributes in parliament for the outgoing Speaker following the announcement.
"I believe that we have had the privilege to serve in the house when we had our finest Speaker," Mr Morrison said.
"I know you haven't arrived at the decision lightly."
Opposition Leader Anthony Albanese said the Victorian MP had been an outstanding Speaker.
"Not everyone who comes in this place is a (parliamentarian) but you are, you respect the history of the Westminster system," he said.
WA Liberal Slade Brockman was elected Senate president last week after Mr Smith's fellow Victorian Scott Ryan brought forward his retirement.
Mr Smith has served in parliament since 2001, and said the timing of him stepping down as Speaker was delayed due to the pandemic.
"Had it not been for the responsibility I've had to the operation of the house during this COVID time, I would have made this speech some time ago," he said.
