The 28-year-old New Zealander will add size, pace and power to the Saints backline as the team prepares for another challenging campaign in Aviva Premiership Rugby, the Heineken Cup and LV= Cup.
Wilson arrives at Franklin's Gardens after a year spent with French outfit Bourgoin. Predominantly a centre, Wilson has also played fly half and full back in his time both at the Stade Pierre Rajon and at former club, Southland.
Wilson became an Invercargill hero when his drop goal won Southland the Ranfurly Shield with a victory over Canterbury this time last year. It capped an eight-year stay at the province for Wilson, who at 6ft 5in and 93kgs adds an intimidating physical presence to the black, green and gold.
He has experienced Super Rugby with both the Highlanders and Chiefs, but is now looking forward to taking on Aviva Premiership Rugby and the Heineken Cup with the Saints.
"Playing in the Premiership has always been a goal of mine and I can't wait to join Northampton Saints," he said. "The history of the club is something that is very special, and the coaches and squad that I am joining are world class.
"I cannot wait to get out in front of the incredibly passionate fans that I have witnessed on TV and run out at Franklin's Gardens."
Director of rugby Jim Mallinder says that Wilson is a good addition to the Saints squad.
"James is an experienced player who has shown his abilities on both sides of the world," he commented. "He reads a game well, brings other players around him into the play and has a strong kicking game, too. We have been impressed with what we've seen of him and believe that he will fit into our patterns of play and give us options."