Draxler, who played for Wolfsburg and Schalke in the Bundesliga, joined PSG in 2017. He made over 190 appearances in six seasons with the Ligue 1 club, but fell out of favour and spent last season on loan with Portuguese side Benfica.
"The club would like to wish Julian all the best for the rest of his career," PSG said in a statement.
Draxler has scored seven goals in 58 international games but has not played for Germany since March of last year. He was part of the Germany squad which won the FIFA World Cup in 2014.
Al Ahli are 11th in the Qatar Stars League following three straight defeats in their opening three league games.