The 22-year-old crosses to the Renegades after stints with the Melbourne Stars and Brisbane Heat over the past two seasons.
Zahir, a left-arm wrist spinner, boasts a bevy of variations and has already made an impact in the BBL.
He has claimed 14 wickets in his 16 games, with his economy rate a miserly 6.76.
“I love the Big Bash so much and was very pleased to sign up for my third season in this great tournament,” Zahir said.
“I am happy the Renegades have given this opportunity to me to show what I can do.”
Zahir has signed for the duration of the tournament.
“We’re excited to welcome Zahir Khan to our Renegades program,” BBL Head Coach David Saker said.
“He has shown some promising signs in the Big Bash over the last two years. He’s a skilful bowler, has plenty of variations and is a young player who will only continue to improve."
“Zahir plays with a lot of energy and we believe he will add a point of difference to our bowling attack," Saker said.
Zahir joins fellow Afghan all-rounder Mohammad Nabi, English fast bowler Reece Topley and Indian batter Unmukt Chand as overseas signings.
Today's news completes the Renegades’ playing list for BBL|11. The club and Victorian spinner Jon Holland have mutually agreed that he will depart the list.
“Zahir Khan’s signing is another important piece of the puzzle for us this season and we’re glad to have him on board,” General Manager, James Rosengarten, said.
"With the additions of Zahir and Mohammad Nabi, our squad is finalised and we're full steam ahead into preparations over the next 4 weeks for BBL to get underway."
“There’s a nice blend of experienced, senior players alongside plenty of emerging talent in our playing group. We’re confident this group is capable of lifting the Renegades back up the ladder this season.”
Melbourne Renegades BBL Squad: Aaron Finch, Cameron Boyce, Unmukt Chand (IND), Zak Evans, Jake Fraser-McGurk, Sam Harper, Marcus Harris, Mackenzie Harvey, Zahir Khan (AFG), Josh Lalor, Nic Maddinson, Shaun Marsh, Mohammad Nabi (AFG), James Pattinson, Mitchell Perry, Jack Prestwidge, Kane Richardson, Will Sutherland, Reece Topley (ENG)