Sissoko, a £2 million 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.
"We had a nice night in the hotel last night, a nice meeting, and you sensed there was a good feeling amongst them all.
"It has been a terrific day for us because we were under a lot of pressure tonight.
"We lost such an important game against Reading that we couldn't afford to lose tonight [Tuesday]. We couldn't afford to draw after going 2-0 up.
"That showed second half when we were a bit rash, lost control, and the French boys certainly felt the difference between the Premier League and Ligue 1.
"Villa came at us full steam and that is where they have to learn quickly. They are both leaving in wheelchairs because they've got cramp!"
Villa have dropped into the bottom three for the third time this season and manager Paul Lambert knows his side cannot afford to perform as they did in the first half.
He said: "We paid the price for starting too slowly. We just never got going in the first half. The second half, that's the way to play football.
"The first goal was really disappointing; the second goal, you sometimes can't stop them - it was a terrific strike - and then you are facing an uphill battle.
"But I couldn't fault them for the way they played in the second half. It is the first time I've seen a standing ovation when you've been beaten, especially at home.
"I just said to the players 'you can't play like that in the first half and turn that performance in during the second half'.
"It is sometimes easier to play when you are 2-0 down because no-one expects anything then. You've got to start like that - and we never started."
Lambert confirmed central defender Richard Dunne has suffered another setback to his groin after already undergoing three operations.