On August 3, after placing catcher Blake Swihart on the disabled list, the Red Sox added Butler to their major league roster. He made his season debut with Boston on August 10, appeared in two games while going 1-for-6 (.167) at the plate, and was then designated for assignment on August 14 when Swihart returned from the disabled list. On August 15, Butler was sent outright to Triple-A Pawtucket. He elected free agency on November 2, 2018. Butler's short stint on the Red Sox's active roster during their 2018 World Series run made him eligible for a championship ring.