The Red Devils secured the title after Rooney's 73rd minute goal, which helped his team overcome South American champions Liga de Quito in the final.
The strike took Rooney's tally up to three Club World Cup goals, earning him the competition's Golden ball.
"We were hoping Rooney and Cristiano Ronaldo will do something special and they did," Ferguson said after the game.
"Rooney scored a great goal and he definitely deserves the best player award. No doubt about that."
Ferguson conceded that he was worried about going into extra-time with ten men, after defender Nemanja Vidic received his marching orders early in the second half.
"I delayed the substitutions as much as possible because I was worried about going into extra-time.
"Vidic's expulsion affected us a bit, but thankfully my team showed a lot of discipline after his dismissal."
The Scot concluded by saying that Asian champions Gamba Osaka were the team that impressed him the most in this year's World Cup.
"You have to complement Gamba, they are a very good team. I watched them against Pachuca where they could have scored 3 or 4 goals.
"None of the Quito players has the same talent as Gamba midfielder Yasuhito Endo."