Mr Neill, Conservative MP for Bromley and Chislehurst, began his political career 50 years ago on Havering Council.
He informed the Bromley and Biggin Hill Conservative Association by letter on February 1 of his intention to step down.
He has since published his resignation letter on X (formerly Twitter).
“After a great deal of thought, I have decided not to stand as a candidate at the next general election,” he said.
“As you know, Ann-Louise has been fighting bravely to recover from the stroke that she suffered a while ago.
“It is a tough road for her, but we are very positive about it.
“Even so, I have concluded that it is now right for me to spent more time supporting her. She has always been there to support me and I want to do the same for her and our family.”
But, he added: “Please rest assured that I will continue to work as actively as ever for my constituents until the day this Parliament is dissolved, whenever that may be.”
Mr Neill won the 2019 general election with 11,000 seats more than Labour.
But polling website Electoral Calculus currently predicts that Labour will win the Bromley and Chislehurst seat at the next general election.
Bob Neill celebrating his victory in the 2006 Bromley and Chislehurst by-election
In the letter announcing his intention to step down, Mr Neill pointed out that this May will mark 50 years since he first took public office as a Tory councillor in Havering.
Born in Ilford, he studied at Abbs Cross Technical High School in Hornchurch before qualifying as a barrister, specialising in criminal law.
He was first elected to Havering Council in 1974 and remained on the council for 16 years.
He also represented Romford on the Greater London Council for two years.
After unsuccessful bids in Dagenham in the 1980s and Tower Hamlets in the 1990s, he was elected as Bromley’s assembly member in 2000 and went on to become the assembly’s Conservative group leader.
He became the Bromley and Chislehurst MP in a 2006 by-election and has held the seat ever since.
In government, he has served as a shadow minister for housing and then as Parliamentary Under Secretary of State for Housing, Communities and Local Government.
He was knighted in 2019 for his services to politics.
That was the same year his wife Ann-Louise suffered a stroke.
“For the last 24 years it has been my enormous privilege to serve the people of Bromley,” he wrote in his letter.
“I have had the honour of serving as a minister, as a vice chairman of our party and, for the last nine years, as chair of the justice select committee.
“Throughout that time, I have been fortunate to enjoy the consistent and warm support of our local Conservative Association’s officers and members, for while I am profoundly grateful.”
He added that until he steps down, he will give his “full support to the Prime Minister, who is giving the country the honest, diligent and pragmatic leadership that our country deserves”.
