Jones, 25, was selected by the Chargers in the third round of the 2018 draft out of North Carolina State. He played in 51 games with 35 starts the past four seasons, recording 63 tackles, 4.5 sacks, 12 tackles-for-loss, two pass breakups, two fumble recoveries and one forced fumble.
"Justin is a big, physical and long interior player that can cause disruption in both the run and the pass," said general manager Ryan Poles. "We would like to thank Jared Fox at Sports Stars for helping bring him to Chicago."
Jones told reporters Friday at Halas Hall that he was planning to sign with the Colts before he received a phone call late Thursday night from Bears coach Matt Eberflus.
"He told me, 'Look, this will be a great opportunity for you,'" Jones said. "He said, 'I really think you fit right in with our guys, you fit right in with our scheme, you fit right in with what we're trying to accomplish. The way you go about your work … as a character, as a man, it just fits in with what we have going on over here with the Bears.'"
Jones was swayed by Eberflus' impassioned words.
"I just fell in love with the conversation we had and I believed in what he was talking about, and here we are today," Jones said.
"He didn't press me to make a decision, but he did tell me, 'Hey, this would be a great opportunity for you. The guys here are amazing. The facilities are amazing. The staff here is amazing. Training staff, coaches, it's a family atmosphere, from the top with the owners and the GM to the bottom to the players.' That's one thing I'm big on, family. Just for me to be able to come and fit in and be a part of this puzzle, that's amazing.
"When he called I could feel the passion and I could feel what he was talking about when it comes to playing for each other, playing for a family, being with an organization that's family-owned."
After appearing in 15 games as a rookie, all as a reserve, with the Chargers in 2018, Jones opened 35 of the 36 games he played over the past three seasons. Last year the 6-3, 309-pounder established career highs with 37 tackles and 3.0 sacks and matched a career high with five tackles-for-loss.
As a player, Jones described himself as an explosive, energetic, fun-loving team guy who loves to win games.
The Bears signed Jones hours after announcing they weren't going to sign unrestricted free agent defensive tackle Larry Ogunjobi, who had agreed to a three-year contract earlier in the week, due to a failed physical.
Jones has worked out with Ogunjobi in the past and knows him through Bengals defensive tackle B.J. Hill, who played against Jones at rival high schools in South Carolina and with him at North Carolina State. Jones described Ogunjobi as "a hell of a player" who "made a lot of plays last year." He also said their playing styles are similar.
"What happened with Larry is terrible," Jones said. "He's a great guy.
"He deserved everything he was about to get. That's just terrible how that went about. But it's an opportunity that I can take advantage of, and I'm really excited to be here, really excited to get to know these guys, get to work with these guys and just show them that, 'Hey, I'm here to win games with you guys, I'm here to win a championship and I'm here to put on a show for these fans.'"
Jones flew to Chicago from his home in South Carolina Friday. When he arrived at Halas Hall, he entered through a hallway that's lined with the names and numbers of Bears Hall of Famers.
"It's a great deal of history that comes through these walls," Jones said. "When I walked in through the main entrance and saw all the history from Walter Payton, that's a household name and everybody knows the type of guy he was. The amount of kids that wanted to be like him, the amount of people who wanted to take after his work ethic and everything, I can tell that's in the threads of the DNA that's in this organization, and I want to be a part of that."