Sissoko, a £2million capture from Toulouse, set up the opening goal for Papiss Cisse and impressed in his central midfield role.
Yohan Cabaye's stunning strike doubled the Magpies' lead and all Villa could manage in a second-half fightback was Christian Benteke's penalty.
Pardew, who also gave a debut to another French player in Yoan Gouffran, was surprised at how quickly the newcomers slotted into his side.
He said: "When you are looking for players and trying to find the secret ingredient for your team, it's not always easy for players to come and fit in as they did in the first half.
"I was a little bit surprised myself if I'm honest. I don't think we would have won the game without Sissoko. That's how important I think that signing was.
"Sissoko really grabbed the game by the horns and that's what we needed.
"With Demba Ba departing from a team that hasn't been winning, it was a big blow for us and we really needed him for this game."
Pardew added: "We have worked really hard on integrating the new players.
"They are not here to save us, they are here to help us. That was my message to the established players."