The Red Sox just landed the top remaining bat in free agency.

Boston and third baseman Alex Bregman agreed to a three-year, $120 million contract, The Post’s Jon Heyman confirmed.

The deal has opt-outs after each of the first two seasons.

The Athletic was the first to break the news.

According to Heyman, Bregman turned down a six-year, $171.5 million offer from the Tigers to instead sign with Boston.

He had been looking for at least a six-year deal but settled on the gaudy $40 million average annual value with the Red Sox.

The Tigers, Cubs, and Astros were among the teams interested in his services, Heyman previously reported.

Bregman, who turns 31 at the end of March, was viewed as the best bat available on the market after Pete Alonso re-upped with the Mets last week.

The two-time All-Star — drafted No. 2 overall in 2015 — provided consistency in the Astros’ lineup since his call-up in 2016 and was in the middle of their two World Series-winning teams in 2017 and 2022.

He hit 20-plus homers in each of the last three seasons and posted .260/.315/.453 slash line last year.

How the Red Sox manage their defense and lineup is an interesting question mark, as they already have stars Rafael Devers and Triston Casas at third and first base, respectively.

According to ESPN’s Jeff Passan, Bregman is expected to play second base, a position he’s played all of 32 innings at the big league level.

Bregman has spent the bulk of his career at the hot corner and won his first Gold Glove at the position last season.

He ranked in the 91st percentile in outs above average last season, per MLB’s Statcast.

The Red Sox, hoping to improve upon their 81-81 finish last season, signed Dodgers World Series hero Walker Buehler and traded with the White Sox for an ace in Garrett Crochet to fortify the starting rotation.

They also inked former Yankees reliever Aroldis Chapman on a one-year deal.