It took almost three years, but Steve Cohen finally got his man.

David Stearns will be the Mets’ new president of baseball operations, The Post’s Joel Sherman confirmed, after reaching agreement with the club on a five-year contract.

Stearns will start with the Mets in his new role at the end of this season.

The 38-year-old Stearns spent this year as a consultant with the Brewers after heading the team’s front office for seven seasons as general manager and later president of baseball operations.

Under Stearns, the Brewers reached the postseason four straight years from 2018-21, advancing as far as Game 7 of the NLCS in 2018.

Milwaukee failed to get to the playoffs last year — in part because of a trade deadline move that sent closer Josh Hader to San Diego that proved to be damaging to the team and may have played a role in Stearns leaving his position after the season, when he moved to an advisory role with the organization with a year remaining on his contract.

But there was a lot more good than bad from Stearns with the Brewers.

After reaching the playoffs just four times in the franchise’s history before Stearns’ arrival, they got there four times with Stearns.

The Harvard graduate, grew up in Manhattan rooting for the Mets and interned for the club after college.

He became the youngest GM in the game in Milwaukee in 2015, when Stearns was just 30. He was promoted to president of baseball operations in 2019.

Cohen had interest in hiring Stearns away from the small-market Brewers upon buying the Mets after the 2020 season, but was denied permission by Milwaukee to speak with him.

The following offseason, Cohen again looked into hiring Stearns, but the Brewers declined to allow Stearns — who grew up on the Upper East Side — out of his contract.

After a protracted search, which included the hiring — and dismissal — of both Jared Porter and Zack Scott, the Mets hired Billy Eppler and gave him the GM title.

But Cohen maintained a desire to bring in a president of baseball operations above the GM.

Stearns’ contract with the Brewers allowed him to begin speaking with interested teams following the Aug. 1 trade deadline.

The Astros (for whom Stearns worked as an assistant GM before going to Milwaukee) also showed interest, according to a source.

Stearns is expected to keep Eppler as his top lieutenant in his current GM role, but manager Buck Showalter’s future with the organization is murkier.

Whether Showalter remains to fulfill the final year of his contract might hinge upon whether Stearns alone is entrusted with the decision or if Cohen will have final say.

Cohen is believed to have a strong affinity for Showalter, who guided the team to 101 victories last season.

Stearns could push to hire Craig Counsell, whose deal with the Brewers is set to expire after the season.

Counsell and the Brewers recently broke off contract negotiations.

Whoever is in the manager’s seat, Stearns will have to rebuild a Mets’ team that wildly underachieved this season, despite a record-setting payroll.

Cohen and Eppler have both indicated the team won’t be as active at the top end of the free-agent market this offseason, but the Mets will continue to have a significantly higher payroll than anything Stearns ever worked with in Milwaukee, where Stearns was known for making savvy trades — including the acquisition of Christian Yelich from Miami prior to the 2018 season in exchange for four minor leaguers.