By Ali Stokes
The English-born 25-year-old gives the Falcons a quality option at fly-half and full-back, with the ability to play right across the back line.
Swiel has spent the past four seasons with fellow Gallagher Premiership Rugby club Harlequins after joining them from South African Super Rugby side the Sharks, having previously played Currie Cup rugby for Western Province.
Making 48 appearances for Harlequins, including 30 in the Premiership and a further 12 in Europe, Swiel joins Newcastle with immediate effect.
Falcons director of rugby Dean Richards said: "Tim is a player I've admired for some time.
"He plays the game at pace, he is someone who makes things happen in attack and he will fit perfectly into the way we play.
"The fact that he can play multiple positions is another major plus point, and we look forward to seeing him being integrated into our squad."
Swiel said: “I have thoroughly enjoyed my time here at Harlequins with a great bunch of lads. I will take some very special memories with me, particularly from playing in Big Game, against Leinster in the Heineken Cup and very special victories over Saracens and Bath at The Stoop.
“The Club is very ambitious and I hope it gets where it wants to be. It has been a great part of my rugby journey and now I am excited and looking forward to the next part of it at Newcastle.”
Harlequins head of rugby Paul Gustard added: “Tim is a talented and popular player who has contributed to some fine Harlequins memories over the past four years. He has a tremendous opportunity to further his career at Newcastle and we did not want to stand in his way.
“I know I speak on behalf of the team when I say we are going to miss him as a human being first and foremost but on behalf of all at Harlequins I wish him the very best for his future at Newcastle.”