Maguire, 28, has become a crucial figure for Ole Gunnar Solskjaer since his whopping £80m move from Leicester City in 2019.
The England international captained United to second place in the Premier League and the final of the Europa League last season.
But Maguire was an unused substitute in United’s Europa League final defeat to Villarreal in Poland in May, despite suffering ankle ligament damage.
The United skipper missed England’s opening Euro 2020 win over Croatia due to an ankle injury.
Maguire was on the bench for the 0-0 draw against Scotland at Wembley, but he has since returned to the England starting XI under Gareth Southgate.
However, the former Leicester star is still waiting to lift his first piece of major silverware for club or country.
Now, the 39-year-old former United captain claimed Maguire looks “confident and comfortable” for England.
Vidic awarded the England star an eight out of 10 rating, adding that Maguire is “still improving.”
He wrote for The Athletic: “Harry Maguire looks confident and comfortable, even more for his country than for Manchester United.
“He’s a defender who is still improving, but if he wants to be recognised at the highest level he has to win trophies. When I look at Maguire I see a defender who is good at everything, 8/10 at everything.
“He’s not as good on the ball or as fast as Rio Ferdinand was for example, and he doesn’t tackle or head like I did, but he has quality across his game.
“He’s fast enough, he’s strong enough, he can jump and play the ball, his positioning is fine.”
Vidic praised the 25-year-old United left-back after he “improved a lot defensively.”
The former Serbia international said: “Shaw came to United just after I left. He has suffered from injuries but was one of United’s best players last season.
“We always knew Shaw was dangerous in attack but he’s improved a lot defensively, especially his positioning and especially when his team play three at the back.”