The deal includes an opt-out in 2030 and will begin starting with next season.
It is now the largest contract for a pitcher with four or more years of service, with the previous being Texas Rangers pitcher Jacob DeGrom with $137.5 million.
Crochet was previously acquired in a trade with the Chicago White Sox during the offseason.
He was on a one-year contract worth $3.8 million with a third year of arbitration set for 2026 before becoming an unrestricted free agent in 2027.
Now, he'll be under contract until 2031, barring the opt-out.
During his first start this season for the Red Sox, Crochet went five innings, giving up just two runs on five hits with two walks and four strikeouts.
In 2024, Crochet went 6-12 on a White Sox team that set the record for most losses in a season.
Despite the record, Crochet was an All-Star who finished the year with a 3.58 ERA with 209 strikeouts and just 33 walks in 146 innings pitched.