Casemiro and the red-hot Marcus Rashford scored early in the first half as the Red Devils defeated the Magpies 2-0.
Despite Manchester United ending their six-year trophyless drought, manager Erik Ten Hag acknowledged that his side did not have the best performance in the Carabao Cup final against Newcastle at Wembley on Sunday.
Casemiro and the red-hot Marcus Rashford scored early in the first half as the Red Devils defeated the Magpies 2-0.
"It was not always the best football, but it was effective, and we again had the right spirit. We have a perfect spirit to fight and give everything," Ten Hag said to Sky Sports.
It was a hard-fought victory for Manchester United, with Newcastle the better team in possession, especially in the second half.
Eddie Howe's charges tried all they could to come back into the game, but Manchester United, who played as a collective, were smart enough, especially in defence.
"They are outstanding collectively, but they also challenge each other, which needs to happen," Ten Hag noted.
"It is a good dressing room, and when it is difficult, they help each other. It is great to see, and I think it is the best a manager can get."
Casemiro not only scored the opener but was pivotal in the defensive midfield. Defender Raphael Varane and goalkeeper David De Gea were also crucial in executing their roles.
And the Dutchman showered them with praise: "Varane, Casemiro, and De Gea know how to win trophies, and you need such players on the pitch to lead the team."
"They have a winning attitude; they have to bring it in the dressing room, in difficult situations, and that is what they have done."
Before, Man United had last won a major trophy in 2017 under Jose Mourinho, the UEFA Europa League.