Dodgers president of baseball operations Andrew Friedman announced the pact on Monday.
"When I was hired to lead this team three years ago, I said at the time that managing the Dodgers is truly the opportunity of a lifetime, and I feel the exact same way today," Roberts told the team website.
"We've worked hard to develop a team and culture that will put us in position to win the World Series every season, but we still have yet to achieve our ultimate goal and that is what drives me each day. I want to thank Andrew, Stan Kasten and our outstanding ownership group for believing in me and keeping me in Dodger Blue, a uniform I'm so proud to wear."
Roberts has led the Dodgers into the playoffs in each of his three seasons with the club, the first skipper to ever do that for the franchise to start his tenure. The 46-year-old helped the National League West power reach the World Series in 2017 and 2018.
Roberts owns a 287-200 record during his three seasons with the Dodgers.
The franchise exercised its 2019 option on Roberts in November, while working out a long term deal. Los Angeles also lost general manager Farhan Zaidi to the San Francisco Giants, third base coach Chris Woodward to the Texas Rangers' manager job and hitting coach Turner Ward to the Cincinnati Reds.