The fuzzy-haired Belgian midfielder, who joined United for £24 million on the final day of the transfer window, gave his first news conference since joining on Friday and left no one in any doubt about what he will bring to the party.
"I came here to win trophies. For me, it's a dream to join the biggest club in the world," Fellaini, who is in line to make his debut against Crystal Palace on Saturday, said.
"I will prove myself on the pitch. Some people don't like my qualities, but I don't care. The manager, staff and players here know me. The manager gave me confidence (when he signed him at Everton). I didn't know anyone, but he helped me."
"I need to work hard for my place - there are a lot of good players. I need to show my ability, I'll keep focused. I want to help the team and give everything."
Fellaini was United's only high-profile addition to the United squad that won the title last season in former manager Alex Ferguson's swansong.
"Fellaini's presence is very noticeable for many reasons, including his size. But you can't overlook his technical ability," Moyes, who signed him from Standard Liege, said.
"He is effective in different areas of the field. If he keeps improving as he has done, we could have a really top player on our hands. Every time I watch Belgium, Felli is the best player."
Moyes was asked to explain why United had left it so late to sign Fellaini when he had been linked with a move to Old Trafford from the moment Moyes left Everton to replace Ferguson.
"We didn't want to give up on (Everton defender) Leighton Baines so we kept the deals together and only split it (for Fellaini) at the last minute," Moyes said.
Moyes is not sure whether to risk striker Wayne Rooney against Palace, espcially with the Champions League starting in midweek and the derby against Manchester City next weekend.
Rooney missed both of England's World Cup qualifiers with a gashed head sustained in training ahead of the defeat by Liverpool and while the wound has healed Moyes said there was a risk of it re-opening.
"He's in great physical shape but obviously he's got the cut right in the middle of his forehead which could split where the skin is very thin," said Moyes. "He's had the stitches out and it's knitted well.