Burrell has made more than 150 appearances for Northampton since joining from Sale in 2012, helping the Saints to a Premiership and European Challenge Cup double in 2014.
The 31-year-old will complete the season at Franklin's Gardens before officially joining Warrington on July 1 on a deal until November 2021.
"My background is predominantly in rugby league as I grew up in the north, in Huddersfield, surrounded by the sport and playing it at school," Burrell said. "It's never really left my blood; I guess my aim was to always try my hand at it one day and I'm buzzing to get involved with rugby league and the Super League.
"I'm excited about the challenge ahead as it's fresh for me. I've had some great times in rugby union, and I've had some adverse times, so for me to have this opportunity to play rugby league and see how far I can get with a great team is exciting.
"I know I will need to earn the trust of my team-mates first and foremost. I also hope to bring some physicality, that edge and the ability to break the line. I've had the opportunity to play for England in union and to play on some of the biggest stages in finals. I'd like to think I can transfer the experience I have gained into rugby league. I'm not here to make up the numbers, I'm coming over and I mean business."
Warrington head coach Steve Price said: "He's a quality signing, being a former England international who has played at the highest level in rugby union.
"It's exciting for Luther to be able to switch codes and to challenge himself in the Super League; in saying that, he has still got a number of games left this season with Northampton. Once that season is completed we look forward to getting him here and involved in our team.
"He'll have to get up to speed with new calls, different team-mates and a different game, so it will take a bit of time to transition, but he's tall, athletic and can play in a number of positions which adds a lot of depth to our playing squad.
"He's had an interest in the game of rugby league from a young age, and is a great coup for our club."
