US-Canada-Mexico bid has long been viewed as the favourite to stage the tournament
The comment from Sheikh, an advisor to powerful Crown Prince Mohammed bin Salman, came as he hosted United States Soccer Federation chief Carlos Cordeiro, who sought Saudi support for the joint bid in competition with Morocco.
"I was pleased to meet with the president of the American Football Association and chairman of the joint bid for US, Canada, Mexico, a strong bid for hosting World Cup 2026," Sheikh tweeted along with a picture of himself with Cordeiro, smiling and shaking hands.
The comment comes as Prince Mohammed is on an elaborate tour of the United States, a key strategic ally and arms supplier of the kingdom.
The most prestigious tournament in football, which will expand to 48 teams for the 2026 finals.
Morocco is in the running to stage the tournament, which will be awarded during a FIFA vote in Moscow shortly before this year's World Cup kicks off in June.
Sheikh has tacitly implied before that Morocco made a mistake when they chose not to side with Saudi Arabia in its feud with Qatar.
Saudi Arabia, the UAE, Bahrain, and Egypt cut diplomatic and trade ties with Qatar last June, accusing Doha of bankrolling Islamist extremists and fostering ties with arch-rival Iran. Doha denies the charge.