Jansen was late reporting to camp after the pandemic-imposed shutdown, suffering with a COVID-19 infection, which affected his conditioning during the shutdown. He appeared in 24.1 innings over 27 games during the season, with a 3–1 record and a 3.33 ERA with 11 saves (3rd in the NL), while leading the National League with 24 games finished. Jansen pitched one scoreless inning in the first game of the Wild Card Series to pick up the save and in the NLDS he allowed two runs to score in innings. He picked up a save and pitched three perfect innings over three games in the NLCS. In Game 4 of the 2020 World Series against the Tampa Bay Rays, Jansen blew his fourth career World Series save, setting a new World Series record. Nevertheless, the Dodgers defeated the Rays in six games, earning Jansen his first World Series ring.