The 37-year-old was part of the team that claimed the Qatar Cup following a 2-1 victory over El Jaish in Saturday's final.
Goals from Baghdad Bounedjah and Jugurtha Hamroun, either side of a Sardor Rashidov strike, were enough for Al Sadd to defeat the holders in Doha.
It is the first piece of silverware Xavi has won since he left Barca in 2015, shortly after their treble triumph in Luis Enrique's first season as head coach.
"The desire of the Al Sadd players was very clear during the match," the former Spain star said after the match.
"I am proud of winning my first title with the team in Qatar. I hope the team continues to perform well in order to win the Emir's Cup.
"I want to thank all the Al Sadd fans who attended the match and supported the team. They had the biggest role in our title win."