The second overall pick of the 2017 NFL draft, Trubisky finished last season 28th in Total QBR (39.4), tied for 27th in touchdown passes (17), and was 21st in passing yards (3,138), 32nd in yards gained per pass attempt (6.1) and 28th in traditional quarterback rating (83.0).
Trubisky, 25, will earn $4.423 million in 2020 and count $9.237 million against the salary cap.
Bears general manager Ryan Pace said last month that Trubisky and Foles will compete for the starting job in 2020.
"We've increased competition at a critical position and we talked to both players, and the way we view this is it's an open competition," Pace said on April 3. "And credit to both those guys for embracing it."
Trubisky underwent surgery in January to repair a partially torn labrum in his left shoulder and is expected to be medically cleared by the summer. He suffered the labrum tear and dislocated his non-throwing shoulder in Week 4 against the Minnesota Vikings, but he missed just one game.
The Bears traded their 2020 fourth-round compensatory draft pick to the Jaguars for Foles and, in the process, inherited a contract that included about $21 million in guarantees. Foles, 31, later restructured the deal to allow him to void either of the final two years, depending on the upside of his performance.
In 2018, Matt Nagy's first season as head coach, the Bears went 12-4 as Trubisky passed for 3,223 yards, 24 touchdowns and 12 interceptions and rushed for 421 yards and three touchdowns. He played in the Pro Bowl after that season.
ESPN's Jeff Dickerson contributed to this report.