Per ESPN's Chris Mortensen, the 56-year-old has agreed in principle to a new deal with Baltimore.
The Ravens said in a statement released on Dec. 21 that Harbaugh would return in 2019 and that the two sides were working toward an extension.
"John Harbaugh will continue as our head coach for the 2019 season, and he and we are working on an extension to his existing contract, which expires after the 2019 season," the team said.
Following a 4-5 start in 2018, CBS Sports' Jason La Canfora reported on Nov. 11 that Harbaugh and the Ravens were "very likely headed to a mutual parting of the ways" after the season.
One source told La Canfora that the coach's odds of being with Baltimore in 2019 were "quite bleak."
The Ravens responded by winning six of their final seven games to capture the AFC North title for the first time since 2012.
One reason Baltimore took off was the spark provided when rookie Lamar Jackson took over as the starting quarterback in Week 11. He's still developing as a passer, but he displayed tremendous playmaking skills with 695 rushing yards on 147 attempts.
Harbaugh, who was hired in January 2008, showed a willingness and ability to adjust his offense around Jackson, and it has paid huge dividends for the team. It may have been a driving force in helping him save his job.
Among current NFL head coaches, Harbaugh is one of only five who has remained with the same team for at least 10 seasons. He owns a 104-72 career record with seven playoff appearances, including a victory over the San Francisco 49ers in Super Bowl XLVII.