The Qatar international midfielder signed a three year deal with the Lions.
The Barcelona legend's first challenge will be against Al Duhail SC in the Champions League round of 16.
The promoted side signed Brazilian defender Bruno Uvini, Spanish midfielders Isaías Sánchez and Cristian Ceballos and Algerian striker Mohamed Benvettou.
Al Rayyan midfielder Daniel Gomo joined Al Sailiya on loan
El-Arabi played the last three seasons with Qatar's Al Duhail appearing in 60 league matches and scoring 76 goals.
The Japanese playmaker was in stunning form at the Copa America.
The FIFPro delegation, comprising Secretary-General Theo van Seggelen, Legal Director Roy Vermeer and Senior Member as well as Services Specialist Simon Colosimo, visited the QSL headquarters.
The former Barcelona and Spain midfield maestro signed a two-year deal.
Akram Afif takes the best player honour.
Akram Afif scored a double as Sadd finish off their league campaign in style
Plenty to play for in the last round of QSL as Qatar SC and Al Kharaityat look to avoid finishing at the bottom.
The Wolves take on the Uzbek side in the AFC Champions League in Tashkent on Tuesday.
Al Sadd defeated Al Ahli in their Week 21 match to take an unassailable lead and regain the league shield.
Baghdad Bounedjah and Co scored a record-breaking 94 goals with a goal difference 73.
Baghdad Bounedjah hat-trick helps Al Sadd crush Al Ahli 7-2 to triumph in style.