Mido's spell with Middlesbrough has been brought to an end with the striker joining Ajax on a free transfer.
The well-travelled 27-year-old has moved to the Eredivisie side on a free transfer having been informed he was not part of Riverside manager Gordon Strachan's plans.
Egypt international Mido spent a two-year spell with the Amsterdam outfit earlier in his career.
Ajax boss Martin Jol believes that his latest addition will give his squad added depth.
He told the club's official website: "We needed an extra striker and we have limited resources which have to be considered."
Mido has had a nomadic existence after leaving Ajax in 2003, playing for Celta Vigo, Marseille, Roma, Tottenham, Wigan, Zamalek and West Ham.