Clarke's current City deal was due to expire this week but he will now remain with the Bantams until the end of the 2016/2017 campaign.
Following the signing of midfielder Nicky Law earlier this Wednesday (story link HERE), Clarke becomes the latest player to take his place in Stuart McCall's squad ahead of the new season.
Clarke said: "I'm glad to get the contract signed. It was always a simple decision for me to stay with Bradford.
"We did well as a defence last season and it is something we'll be looking to carry on into next season.
"I'll be the same as everyone else come pre-season, eager to impress the new manager from day one.
"I want to be up at the front and in the manager's thoughts as much as I can be.
"The aim is to hit the ground running this year. I got off to a slow start last year but I felt I picked up from Christmas onwards really and did quite well in most of the games.
"I'll be looking to get out there (on the pitch) as much as I can and hopefully contributing to a fantastic season."
The 32 year-old made 31 appearances for City last season, including both Play-Off semi-final matches, arguably becoming one of the club's more impressive performers in the latter stages of the campaign.
With Clarke in the side, City picked up eight wins from eleven games towards the end of the regular league season, conceding only four goals in the process.
The central defender originally signed for the Bantams from Leyton Orient in July 2015.