The 29-year-old defenseman had been in training camp with the New York Islanders on a professional tryout (PTO) but was released from that contract Sunday.
"I got the news Friday that Chicago wanted me back and Islanders, I had a great camp there, it's a great organization over there, players and leadership too," Gustafsson said. "But they didn't have any [NHL salary] cap space ... so I'm very happy to be here. It was a quick decision but I'm very happy to be here."
Gustafsson scored 12 points (one goal, 11 assists) in 29 games for the Philadelphia Flyers and Montreal Canadiens last season, and three points (one goal, two assists) in 16 Stanley Cup Playoff games to help Montreal reach the Cup Final, when it lost to the Tampa Bay Lightning in five games.
The Blackhawks will start the season without defensemen Wyatt Kalynuk and Caleb Jones. Kalynuk is expected to be out 2-4 weeks with a sprained right ankle and Jones will be out about six weeks with a left wrist strain. Each player was injured last week.
Chicago opens the season at the Colorado Avalanche on Wednesday (10 p.m. ET; TNT).
"He's comfortable and excited to be here and he also understands what he's coming into," Blackhawks coach Jeremy Colliton said. "Nothing's been promised as far as what exactly his role is going to be, but we do think he can help and it's kind of up to him. Certainly nice to get him in here for a couple of days. I don't know if he'll play Wednesday, but we'll go from there."
Gustafsson made his NHL debut with the Blackhawks during the 2015-16 season and played his first four NHL seasons for Chicago. In 2018-19 he tied for third among NHL defensemen with 17 goals and was sixth with 60 points.
He said familiarity with Colliton made Chicago a desirable destination. Gustafsson played for Colliton with the Blackhawks and Rockford of the American Hockey League.
"He's seen my worst games, my best games, he's talking to me a lot," Gustafsson said. "Probably talked to me 4-5 times today. We know each other a lot so yeah, that's one part of [why] I wanted to come back here too. You know the guys, the facility, know the United Center, the city and just focus on hockey right away. Don't have to think about other stuff."
Selected by the Edmonton Oilers in the fourth round (No. 93) of the 2012 NHL Draft, Gustafsson has scored 131 points (29 goals, 102 assists) in 250 regular-season games with the Blackhawks, Calgary Flames, Flyers and Canadiens, and eight points (one goal, seven assists) in 31 playoff games.
NHL.com staff writer Tracey Myers contributed to this report
