A source told ESPN.com the deal is worth $5.4 million on average per season.
The timing was key. Jones would have been a restricted free agent on July 1, and there were rumblings of a potential offer sheet finding its way to him.
"Acquiring Seth Jones was very important to our organization, and reaching a long-term agreement with him to remain a Blue Jacket was a priority, so we are extremely excited about having done so today," Blue Jackets general manager Jarmo Kekalainen said. "At 21, Seth is just beginning to tap into his potential as a player. He has everything you look for in a defenseman and is going to be a very important player and leader on our team for many years."
Jones was acquired from the Nashville Predators midway through this past season in a stunner of a trade in exchange for No. 1 center Ryan Johansen. Jones was the No. 4 pick of the 2013 NHL draft. He had 31 points (3-28) in 81 games overall this past season.
After signing the deal with Jones, the Blue Jackets bought out the final two years of defenseman Fedor Tyutin's contract to give themselves some cap space.
The 32-year-old Tyutin, acquired in a trade with the New York Rangers in July 2008, ranked second on the Blue Jackets' all-time games-played list behind Rick Nash.