The central defender was Chelsea’s captain for the match at Stamford Bridge and believes the new Blues boss has turned the club around.
Conte recently changed his formation to using three at the back, a tactic which has helped Chelsea keep three clean sheets on the bounce in the Premier League.
Cahill told the club’s website: “He’s an experienced manager and you have to buy into his ideas, we’ve done that.
“We’re managing to build from the back and get out quite easily and for me, it’s nice we’ve tightened up.
“A few weeks ago it was doom and gloom but look at the league table. Ultimately it shows character.
“We dominated [Man United] from the first minute to the last and it was really impressive”
Chelsea ace Gary Cahill
“We’ve stopped letting goals in and naturally that breeds confidence. We need to stay in contention, stay up there.
“It’s going to be tight until the end of the season because there are some terrific teams up there.”
Cahill was also impressed with the way Chelsea thrashed United and dominated for the full 90 minutes.
He added: “First and foremost winning the game was the most important thing but the performance that went with it was fantastic.
“We dominated from the first minute to the last and it was really impressive from us. We’re very pleased and I’m delighted with the attitude shown by the boys.
“It was the way we wanted to start the game, we wanted to be sharp and that’s what Pedro was.
“He was first to react and bang, it was 1-0. We played well, we played with confidence and overall it was probably our best performance of the season.”
The victory leaves Chelsea in fourth place just a point off the top of the table.