The Premiership side's official site stated that the club had to wait until the deal was finalized on Monday to unveil Zaki, who was dubbed as the 'Egyptian Gladiator'.
Zaki's move, which was described by Wigan as 'one of the longest running transfer sagas in the club's history', witnessed a number of stumbles before an agreement was reached.
"It's been a real tough deal to push through, that's for sure, but I'm delighted that Amr's finally a Wigan Athletic player. Everything has been sorted, and now he can just get on with the job at hand," said Latics boss Steve Bruce.
"Although he hasn't played in the Premier League, I am convinced, having seen him personally on several occasions that this boy can do the business.
"I think our supporters will love him because he's a passionate boy who plays with his heart on his sleeve. He is all- action; physically powerful, great in the air, with two great feet and a good turn of pace."
Zaki has been pleading for a move to a bigger club since joining Zamalek in 2006, and the tenacious forward is now handed the opportunity to shine in one of top league competitions.
"I've come to England to score goals. That's what I do. I want to show the manager and the fans of Wigan that they have made a good choice and now I am totally focused on trying to get in the squad and prove myself here," said the 25-year-old.