The winger completed a move from Bournemouth on Friday.
Matt Ritchie celebrates scoring the first goal for Bournemouth
The winger completed a move to St James’ Park on Friday, becoming their third signing of the summer transfer window.
He has agreed a five-year deal at the club as Benitez looks to build a squad capable of dominating the Championship next season.
Newcastle United's Andros Townsend looks dejected
He has been brought in as a direct replacement for Andros Townsend, who ended his short stay in the North East when he completed a switch to Crystal Palace on the same day.
And Benitez says that as soon as they knew the former Tottenham Hotspur man was moving on, they made securing Ritchie a priority.
“As soon as we knew that Andros Townsend could be leaving, our priority was to finalise this deal,” he told nufc.co.uk.
"We have signed an exciting winger who has experience in the Championship but has also proved that he can step up to the top level. I am delighted that he is now part of our squad."
Bournemouth's Matt Ritchie in action
It now remains to be seen whether Ritchie can help to fill the hole that has been left by Townsend’s departure.
The winger was a huge hit at the club after arriving in the January transfer window and Ritchie has big shoes to fill despite Townsend’s relatively short stint at the club.
He will be confident of doing so though, having impressed during his first year in the Premier League last season and more than capable of replicating that in the Championship.
Bournemouth's Matt Ritchie applauds the fans after the game