According to a statement on the Nantes website, Wihelmsson has decided to move to the Saudi League, following successful negotiations with Al Hilal representatives.
Al Hilal, 11 time winners of the domestic league, announced Wihelmsson's signing on Tuesday morning.
Wihelmsson, who was in Sweden’s squad for Euro 2008, started his career with Mjallby in 1997, playing for three seasons.
He transferred to Norway with Stabek and joined Anderlecht in 2003. The winger, who is known for his explosive pace, signed for Nantes in 2006. However, he failed to hold down a regular starting place at the club.
Loan spells at Roma in Italy, Bolton in England and Deportivo La Crouna in Spain, did not materialise into permanent deals for Wihelmsson.
The 28-year-old inked a two-year contract with Al Hilal reportedly worth US$5 million.
Wihelmsson has been capped 50 times by Sweden, scoring four goals.