A host of clubs were linked with the talented Egyptian, after Ajax announced he would no longer figure in their plans.
He spent the end of last season on loan at Celta Vigo, who were keen to keep him, whilst Roma were also said to be interested.
However, Marseille came in with an impressive proposition and persuaded the forward to move to Stade Velodrome.
L`OM sent a delegation to Cairo over the weekend and Mido signed a five-year deal at the Marriot Hotel in the Egyptian city.
"It's a proud moment in my career," Mido told his personal website.
"Marseille is a place that I feel I can progress and improve my game," he added.
"It's another chapter in my life and I'm looking forward to accomplishing great things with my new team-mates."
Explaining why he signed for Marseille, Mido added: "They are a famous club in Egypt. The supporters and the stadium are also beautiful; they are one of the biggest clubs in Europe."
Mido, who will wear the number nine shirt, is looking to put his problems at Ajax behind him.
He added: "I am delighted to come to Marseille especially after the problems which I had with the trainer of Ajax (Ronald Koeman). But I would like to now concentrate only on my football."
Meanwhile, reports from the south of France are suggesting that Manchester United and Newcastle target Daniel van Buyten has agreed a three year extension to his contract.
