The 32-year-old Australian-born utility back has scored 217 points, including 12 tries, in 50 European appearances for Connacht Rugby, Munster and Stade Francais Paris.
Head Coach Richard Hill said: "Paul is a winner, very serious about his rugby and very competitive. His attitude is absolutely spot-on for the culture we are developing at Sixways.
"I want players here with a winning mentality. That's not just a phrase you throw about; you have got to do something about it to achieve it. You have to study the game and your own performances to get better and truly push yourself.
"Paul wants to win rugby matches and that mentality and professionalism is massive.
"I want Paul to play outside half because he will bring other people into the game. Players will improve around him.
"He can put people through holes, can beat defences and offload in the tackle. Everybody will be able to play off him and he is an unselfish player who will bring the best out of the Warriors.
"Paul is a versatile player and attack minded, he is someone who will look to really fire our back line."
The announcement of the capture of Warwick comes just days after confirmation that Argentina international back row Leonardo Senatore had also been recruited from next season.