On January 11, 2019, the Boston Red Sox come to an agreement with reigning MVP Mookie Betts, signing him for $20 million, the most ever given to a player in his second year of arbitration eligibility; in fact, the amount beats that given to any player in his third year of eligibility. Betts will score 135 runs and bat .295 for the Red Sox, his 135 runs scored will be the 5th most in team history. He will also secure his 4th straight Golden Glove and Silver Slugger Award.

Betts will be traded in the 2020 offseason to the Los Angeles Dodgers, he will end his the last 4 years in Boston with 3 Top 10 MVP Award finishes and the 2018 MVP. He lead the Red Sox to a World Championship in 2018 and a club record 119 Wins, tied for the most in a single season.