Cooper Rush signed with Dallas following the 2017 NFL Draft as a rookie free agent with the hopes of earning a shot as a backup quarterback, and he became the only rookie free agent in 2017 to make the active roster out of training camp. He started the season as the club's third quarterback and gameday inactive but earned his shot as the primary backup beginning in Week 7. As a rookie, Rush saw time in just two games, he played in just one game in 2018 and two in 2019 as Dak Prescott's primary backup. He was waived in May 2020, claimed off waivers by the N.Y. Giants and spent the first month of the 2020 season on the Giants practice squad. After the injury to Prescott in Week 5, Dallas added Rush to the practice squad (Oct. 30), where he spent the remainder of the season. He won the job as Prescott's primary backup for the 2021 season, and he was called upon when Prescott (calf) missed the Week 8 matchup at Minnesota (10/31), earning his first career start and leading the team to a 20-16 win over the Vikings. He again earned the backup role in 2022 and saw significant playing time when Prescott missed time with a thumb injury, starting five games and completed 94-of-162 passes for 1,051 yards with five touchdowns against three interceptions - leading the team to wins in four of those five starts and became the first quarterback in franchise history to win his first five career starts. He re-signed with Dallas on a two-year deal during the 2023 offseason.