The German, 38, is expected to be confirmed over the weekend after travelling to England ahead of his unveiling, with Fabrizio Romano reporting the compensation fee owed to his Saudi club — comparable to what Newcastle received for selling Mikel Merino back in 2018.
Jaissle has spent three years at Al-Ahli, winning the Asian Champions League in each of the past two seasons after replacing Pitso Mosimane in 2023, and is well known to Newcastle's owners, Saudi Arabia's Public Investment Fund, who also hold a stake in Al-Ahli's Pro League operations without the two clubs being formally linked.
Before his move to the Middle East, the former Red Bull Salzburg coach won back-to-back Austrian titles and an Austrian Cup, though he remains unproven at the level of Europe's major leagues.
Howe's departure, still to be officially confirmed by the club, follows five years in charge during which he delivered Newcastle United's first major domestic trophy in 70 years by winning the League Cup, along with regular European football.
He had reportedly made the decision to leave before Wednesday's heavy 4-1 pre-season defeat at Bristol City, with Newcastle having offered him a vote of confidence only months earlier.
Jaissle will sign a deal running until 2030, arriving at a club that finds itself in an increasingly tight financial position after a summer of high-profile departures, including the sales of Sandro Tonali and Anthony Gordon and ongoing talks over the future of captain Bruno Guimarães.