Al Nassr will face Saudi Pro League leader and Saudi Super Cup winner Al Hilal in the final on May 31, after it beat Al Ittihad in the other semifinal on Tuesday.
Ronaldo put his side in the lead in the 17th minute after capitalising on a mistake by the Al Khaleej defence.
A poor back pass from defender Lisandro Lopez put the keeper Ibrahim Sehic under pressure, forcing him to loosely clear the ball away, only as far as Ronaldo at the edge of the box. He hooked a left-footed strike into an empty net to take the lead.
Mane doubled the lead from the spot in the 37th minute after Al Khaleej defender Ivo Rodrigues handled the ball inside the penalty area. Mane calmly finished it into the right side of the goal to take a two-goal lead into the break.
Despite making substitutions at the break, Al Khaleej could not stop conceding as Ronaldo finished off a low cross from the right from Aiman Yahya at the far post in the 57th minute.
Al Khaleej goalkeeper Sehic saved his side from further embarrassment as he made nine saves during the match.
Things got worse for Al Khaleej after centre-back Mohammed Al Khabrani was forced off the pitch in the 77th minute due to injury, after the side had made five substitutions, meaning that it had to play the rest of the game with 10 men.
It pulled one back in the 82nd minute through substitute Fawaz Al-Torais, who finished off a fine cross from the right from Arif Al Haydar. But it was too late as Al Nassr comfortably held onto its lead to see off the game.
