The Raptors signed the restricted free agent to an offer sheet on July 13, giving the Indiana Pacers a week to match the offer. They opted not to, clearing the way for Jack to land in Toronto as general manager Bryan Colangelo remakes the Raptors' roster.
"This is another piece of the puzzle that is hopefully going to bring it all together," Colangelo said at a news conference at the Air Canada Centre.
Colangelo also picked Southern California swingman DeMar DeRosan with the ninth pick in last month's draft.
Jack is one of just 11 NBA players who appeared in all 82 games in each of the past two seasons -- last season with Indiana, where he supplanted former Raptors player T.J. Ford for the starter's job, and the previous season in Portland.
"To describe me in a nutshell is 'being tough,'" Jack said. "There are things along the road, going through this NBA journey that you're going to have to play through, and injury and not being 100 percent every night are part of it.
"It's being there for your teammates and trying to be the best teammate possible."
The 6-foot-3, 195-pound Jack, who played with Raptors star Chris Bosh at Georgia Tech, averaged a career-high 13.1 points last season, along with 4.1 assists and 3.4 rebounds. He was acquired by the Pacers in a five-player trade a year ago.
Jack can line up at either point guard or shooting guard, where the Raptors lost starter Anthony Parker to Cleveland, and is known as a hard-nosed defender.
"I just remember coaching and calling out plays, he was picking up our guys and looking over and stealing plays and relaying them back to his teammates and always talking," Toronto coach Jay Triano said in Las Vegas, where he is working with USA Basketball this week. "He just showed me he was very prepared for the games, very much a leader with his team because he really communicates."
Jack has also earned a reputation around the league as a great teammate in the locker room. He says he gets his generous nature from his parents, dad Carlton, a former football player at Grambling State, and mom Louise.
"My parents growing up, whenever my father would cook in the neighborhood, he would cook for anybody who needed a plate. If you didn't have a plate that night you knew there was more than enough food at the Jack household," Jack said.
"My mom would help run our youth basketball association. If there was a kid who had a tough household, come on in our house, we might not have a bed for you, but we make room. We'll get you extra shoes if you need that. ... anything to help put someone in a successful position."