Bridcutt cost Sunderland £3.2m and was one of five January arrivals at the Stadium of Light.
The 24-year-old midfielder was reunited with former Brighton & Hove Albion manager Gus Poyet on transfer deadline day, and the Uruguayan had no hesitation throwing him into the Tyne-Wear fire at St James' Park.
Poyet said after the game: "Some questioned if he was good enough for the Premier League. They won't be asking that question any more, will they?
"He was superb against Newcastle."
Liam Bridcutt: "If someone tells you you're going to win 3-0 on your debut against Newcastle, you'll take that! I was straight in at the deep end really.
"Gus has brought me in here to have a great opportunity to play in the Premier League and it doesn't get any better than that - making your debut in a derby and winning 3-0. It was a bit of a shock, but it was a good surprise for me really.
"We got a clean sheet and that was a massive positive for us. We dominated the second half, particularly towards the end of the game. We could have had a few more opportunities to score."