The 30-year-old started his career with Belfast club Malone and made his mark on the world stage when he was named man-of-the-match in Ireland's win over Australia at Lansdowne Road in November 2006.
"I'm delighted that Neil Best has decided to join Warriors next season," said Director of Rugby Mike Ruddock.

"He is a highly respected figure in British and Irish rugby and brings with him a wealth of experience at international level and no nonsense approach combined with intelligence and skill.

"Neil is just the sort of player we need in our squad and I know he will add leadership to our team and will always lead from the front.

"This is a great signing for Worcester Warriors and we look forward to welcoming him to Sixways."

Best, who also played for Ireland A in the 2008 Churchill Cup and joined Northampton at the start of the 2008/09 season, said: "In terms of the city, Worcester has a real rugby feel to it, very much like Northampton, and the club is held in high esteem by the people who really want it to do well," he said.

"I met Mike Ruddock and, although I knew about him as a coach and his ethos, his passion and ambition for success can only rub off on you. Everyone is singing from the same hymn sheet and keen for success, that makes you want to play for the club.

"I will leave Northampton at the end of this season with very fond memories. I have lots of friends at the club and got on very well with the coaching staff. I'm a professional will do absolutely everything I can to make sure the club is now as successful as we can be this season.

"After that I have a new challenge at Worcester Warriors from next season and I'm looking forward to it."