The 25-year-old hooker joined the Saints in midway through the 2008/09 season, with the last of his 68 appearances coming in January's LV= Cup trip to Bath. Since then a knee injury has ruled him out of action, and with no immediate prospect of Sharman returning to full fitness the decision was made to terminate his contract.
"It is always a shame when someone's contract comes to an end in these circumstances," commented director of rugby Jim Mallinder. "Brett has contributed a lot to the squad in his time at Franklin's Gardens and we wish him all the best for the future."
"I've enjoyed my time at the Saints," Sharman said. "It is a great club with good people and I am sure that there will be major success coming to Franklin's Gardens sooner rather than later. The players, management and supporters all deserve that and I wish them every success."