The deal includes a full no-trade clause, a source told ESPN's Kiley McDaniel.
Swanson, 28, immediately becomes one of the key faces for the Cubs' rebuilding effort as he arrives in Chicago as a reigning Gold Glove winner with a World Series ring to his credit.
He hit .277 with a .776 OPS for the Atlanta Braves last season while playing 162 games. He played in 160 games in 2021, helping the Braves to a World Series championship. He's a career .255 hitter with 102 home runs over seven seasons. Fifty-two of those homers came over the past two years.
Swanson's career OBP, however, is just .321 as he walked only 49 times while striking out a career-high 182 times in 2022.
He'll take over shortstop for the Cubs while Nico Hoerner moves back to second base, where he was a Gold Glove finalist in 2020. The team also signed former Gold Glove winner Cody Bellinger to play center field, giving them a solid defender at that key position as well.
The Cubs have been under pressure to improve a 74-win team but hadn't signed a big name free agent in several seasons. The $177 million deal is the largest given out by the Cubs since outfielder Jason Heyward agreed to an eight-year, $184 million contract in 2016.
Swanson was the last of the four star free agent shortstops to sign. The position earned over $1 billion in free agency this winter just from Carlos Correa ($350 million), Trea Turner ($300 million), Xander Bogaerts ($280 million) and Swanson ($177 million) alone.
The move shores up the Cubs defense but doesn't fix all their offensive issues. The team needs left-handed power, as well as a new catcher after not re-signing Willson Contreras. Prospect Matt Mervis is expected to get a chance at first base next season while the Cubs are still likely to trade for or sign a veteran first baseman -- and another catcher. Yan Gomes is a veteran holdover from last season but isn't an everyday player.
The Cubs are also still looking into the free agent pitching market but can check off a big offseason box: bringing a star caliber player to the team.
Swanson will join wife Mallory Pugh in Chicago as she plays for the Chicago Red Stars, the women's professional soccer team.