The world class leg-spinner will join the club for first nine Blast fixtures, starting with Durham Jets’ away fixture against Yorkshire Vikings on July 5 and he will be the club’s second overseas signing of the 2018 season.
Tahir is currently ranked as the world’s number seven Twenty20 international bowler and has played over 200 T20 games as a professional, taking 203 wickets.
The 39-year-old has featured in 33 T20 Internationals, 85 ODIs and 20 Test Matches for South Africa and claimed 253 wickets across all three formats.
"I’m really excited to be heading to Durham for the Vitality Blast,” Tahir said.
“I always enjoy playing in England and hope that my previous international and county experience can help make an impact.
“I look forward to joining up with my team mates and the rest of the staff at the Emirates Riverside imminently."
The white-ball specialist has a wealth of experience and featured in this year’s IPL for 2018 winners the Chennai Super Kings.
He also has a strong knowledge of English cricket having played for Derbyshire, Hampshire and Nottinghamshire in recent years.
Durham County Cricket Club Head Coach, Jon Lewis, said: “We wanted to invest in a top-quality player to improve our white ball squad and we feel that Imran demonstrates our ambition to compete in the T20 format.
“We were keen to strengthen our squad with an experienced big-game player, who will also be able to help our talented youngsters and look forward to welcoming him to Emirates Riverside.
“He is one of the best leg spinners in the world and will bring a different dimension to our game.”