The deal does include two opt-outs including after three years, but the second one has yet to be determined.
Heyward spent just one season with the Cardinals, recording 13 home runs and 69 RBIs to go along with a .293 batting average. He led the charge during St. Louis's 2015 which saw them post a major league-best 100-62 record.
Reports say Heyward took less money to join Chicago as both Washington and St. Louis offered him a $200 million deal.
The plan is for the Cubs to play Heyward in centerfield due to Jorge Soler taking the right field position. It is still a possibility that the team will deal Soler elsewhere. The former Braves' phenom does have the speed to play center, showing that by stealing 20 bases in three of the past four seasons.
His defense also adds to his stock as the two-time Gold Glove winner posted a WAR of 6.5 in St. Louis.
Chicago completed their second impact-move of the week after signing Ben Zobrist to a four-year deal on Tuesday. Joe Maddon was the big addition last off-season, which led them to a postseason berth in his first year, and the new additions are expected to add to this revamped Cubs organization.