Kendrick participated in 121 regular season games in 2019, finishing with a batting average of .344 in 330 at bats, alongside 62 RBIs and 17 home runs, second-most of any season in his career. He primarily played first base.
On October 9, 2019, in Game 5 of the National League Division Series, Kendrick hit a grand slam in the 10th inning off Los Angeles Dodgers pitcher Joe Kelly to give the Nationals a 7-3 lead that held up as the final score, advancing the Nationals to the National League Championship Series. It was just the second extra-innings grand slam in MLB postseason history, the other being hit by Nelson Cruz in the 2011 American League Championship Series.
Kendrick became a free agent after the 2019 season, but on December 9, 2019, Nationals general manager Mike Rizzo said he had signed a new deal to stay with the Nationals. The contract reportedly covers the 2020 season and will pay Kendrick $6.25 million.