Rafa Benitez reacts to Dwight Gayle's match-winning strike against Bristol City
A first-half strike from Gayle claimed all three points for Benitez's side at Ashton Gate.
Newcastle spent much of the game on the back foot, and were indebted to some dogged and determined defending.
The result lifted the club up to ninth in the Championship.
“We needed to work as a team, and we did that," said United manager Benitez.
"We were analysing things, and we knew it would be a difficult game because they have a lot of big lads up front.
"They played a lot of long balls and set-pieces, and after that they were looking to play. There were a lot of things we had to control, and the only way to do that was to work as hard as we did.
“We’re getting a bit of momentum now, and hopefully we can keep winning.
"Every game is different though, and we know it will be a long, difficult season. The main thing now is that we have to show the same character, personality and work rate as we have displayed in the game today.
“I expected a game like this. From what I have seen of their players and manager, they know what to do and they can change system during the game. They have different options and different approaches, so it was important for us to react well to that."
Mohamed Diame set up fellow new signing Gayle with a superb lofted pass.
And the 25-year-old took a touch before finishing in front of United's 2,501-strong travelling support.
Benitez said: “He (Gayle) has good movements, he is a clever lad, and he is also a great finisher.
"We could see everything today – the movement and the finishing. We are very pleased with him because he has already scored four goals in the league and he has to be a crucial player for us.
"Hopefully, he can continue scoring goals until the end of the season.
“It was good movement, a good pass and a good finish. Everything was nearly perfect, and then we knew that after scoring the goal it would be difficult to keep a clean sheet. But the players worked so hard to do that."