Councillor John Rowley was first elected on Wolverhampton council in 1982, but he was de-selected from his Blakenhall seat in a ballot of ward Labour party members.
It comes amid upheaval among the Labour's ranks in the city that a senior party member has described as being 'like a game of musical chairs'.
Mr Rowley said he plans to lodge an appeal, adding: "I am very disappointed after working hard for the local community for 33 years." He declined to comment further.
Only 36 members of the Blakenhall Labour group turned up to this week's ballot. The group was more than 200-strong at its height but numbers have dwindled over the last year. In 2015 the group was suspended by the party's regional office amid claims of irregularities over membership.
Numbers are now said to be down to around 60.
Wolverhampton's Labour group is in the process of finalising candidates to contest May's local council elections.
Mr Rowley has been replaced by Councillor Jasbinder Dehar, who was recently de-selected from her seat in Bushbury North. Mrs Dehar was subsequently put forward and rejected for seats in East Park, Ettingshall and Bilston East, before landing the Blakenhall seat.
In East Park Councillor Payal Bedi has been de-selected in favour of Anwen Muston, who contested seats in Penn in the last two council elections.
Mrs Bedi has moved over to the Bilston East seat vacated by the late Bert Turner.
One senior party member, who asked not to be named, told the Express & Star: "The process needs to be looked into really because we have a situation where people are going for numerous seats until they finally land one.
"It's a bit like a game of musical chairs."
Changes are also afoot in Oxley, where Councillor Lorna McGregor is to step down. Former Bilston councillor Louise Miles has been selected as her replacement.