The Spaniard has been much maligned for high-profile errors during his time at Old Trafford but has kept four clean sheets this season, including one in United's 1-0 win over Fulham.
"He was superb," Rooney told the club's official website. "I think he's been great for us over the last few weeks as he's made some great saves.
"I know he got a little bit of criticism after the Tottenham game but he made five or six world-class saves in that game and it wasn't the biggest mistake I've ever seen.
"We're all behind him and backing him. He's a great player for us and for the future as well."
Rooney has made 26 appearances for United this season, scoring 16 goals, and has notched 10 in his last 10 games.