Maguire joined Manchester United from Leicester City for £80million.
It broke the world-record transfer fee for a defender that was previously held by Virgil van Dijk following his £75m move from Southampton to Liverpool in January 2018.
McLaren believes Maguire can have a similar impact on United to what Van Dijk has done at Liverpool.
And after watching his man-of-the-match performance against Chelsea on Sunday, McLaren says the 26-year-old can also bring leadership qualities United have been missing.
“The biggest statement of the summer was Maguire,” he said on Sky Sports News.
“He is like Van Dijk signing for Liverpool.
“[Van Dijk was] the difference, the person that took Liverpool to the next level.
“I think Maguire can do exactly the same thing for Manchester United.
“He did it on Sunday against Chelsea, he was magnificent.
“A great centre-back and I think he’s a leader, you could see that.
“He was talking to the players all the time and I think that is a huge, huge signing for Manchester United.
“Everybody needs leadership. A lot of people talk about that the leaders are going out of the game.
“There are many different forms of leadership.
“You can do that by demonstrating how you play, not so much vocally.
“Maguire seems to do it by the way he plays, defends, and the way he talks to the rest of the players and his demeanour, confidence, courage when he has the ball and takes it out of the defence.
“I think it’s the perfect signing for Manchester United.”