The 26-year-old internet personality will replace voice actor Mike Henry in the show’s forthcoming 19th season, which is expected to air in 2021.
Henry stepped down from the adult animation so that the character could be portrayed by a black actor.
Describing the news as a “once in a lifetime opportunity”, Zahir said: “When I heard that Mike Henry was stepping down from the role of Cleveland Brown – my favourite cartoon character of all time – I was shocked and saddened, assuming we’d never see him again.
“When I learned I would get to take over the role? Overabundant gratitude. To Mike, you created something truly special and I promise I will do my absolute best to honour your legacy.”
Zahir has 6.26 million subscribers on his YouTube channel, where he posts videos of his voice impressions.
Cleveland Brown is one of his most popular character impersonations, with Zahir sharing a video dedicated to Henry after it was announced in June that Hanry would be retiring from the role after more than 20 years.
“It’s been an honour to play Cleveland on Family Guy for 20 years,” Henry, who also starred in spin-off The Cleveland Show, tweeted.
“I love this character, but persons of colour should play characters of colour. Therefore, I will be stepping down from the role.”
In the wake of the ongoing Black Lives Matter protests, many animated shows pledged to diversify their voice casts and not have white actors voice non-white roles.
Earlier this week, it was announced that actor Alex Désert would be the new voice of Carl in the season premiere of The Simpsons, taking over from white actor Hank Azaria, who voiced the character for 30 years.