Kahraba, 25, joins the Egyptian Premier League champions on a free transfer after cancelling his contract with Portuguese top-flight side CD Aves via mutual consent.
The 27-time capped Egypt star will officially team up with Rene Weiler's side in January after penning a four-and-a-half-year contract.
The former Zamalek man only joined the Portuguese side in July this year and scored once in five games before expressing his intention to depart.
Al Ahly confirmed the long-term deal on their official website and will be hoping the 2018/19 Confederation Cup winner will boost their ambitions of Champions League success this season.
Kahraba holds a record of 29 goals and 18 assists in 89 games in the Egyptian top-flight for The White Knights and ENPPI respectively.