The fee is structured as a mix of fixed and easily achievable variable amounts, with Trincao, who joined Sporting from Barcelona in 2023 for €18m, set to sign a four-year contract in Jeddah. His wages will rise considerably as part of the move, with earnings expected to be in the region of €10m to €12.5m per season, several times what he currently earns in Portugal.
"I am very proud to join Al Ahli," Trincao said. "I understand the value, history and fanbase of this great club.
"The passion of Al Ahli's supporters was one of the main reasons that pushed me to take this step. I promise to fight alongside my team-mates to achieve success and make the fans happy."
Al Ahli described the signing as part of a broader strategy.
"This deal reflects the club's strategy of strengthening the first team with quality, experienced players, in line with its ambition to compete for every title in the upcoming phase," the club said in a statement.
Trincao leaves Sporting having made 208 appearances across two spells at the club, including an initial loan season in 2022-23, scoring 47 goals and providing 51 assists. His contribution proved crucial as Sporting won back-to-back Primeira Liga titles in 2023-24 and 2024-25, as well as the Taca de Portugal in 2024-25.
A product of Braga's academy, Trincao first moved to Barcelona in 2020 before spells on loan at Wolverhampton Wanderers and then Sporting, where he eventually established himself as one of the Primeira Liga's standout attacking players. The move to Saudi Arabia is expected to be completed once the paperwork between the two clubs is finalised.
The transfer represents Al Ahli's second marquee signing of the summer, following the earlier capture of Armenian midfielder Eduard Spertsyan, and is primarily aimed at replacing Algerian winger Riyad Mahrez, who left the Jeddah club earlier in the window.
Sporting had been bracing for Trincao's departure for some time and have already moved to address the gap in creativity he leaves behind, agreeing a deal worth €30m for Braga playmaker Rodrigo Zalazar earlier this summer.