Carbo was traded along with Rick Wise from the Cardinals to the Red Sox for Reggie Smith and Ken Tatum on October 26, 1973. He said of coming to Boston: "When I first met Sox owner Mr. Yawkey, he was shining shoes in the clubhouse," said Carbo, "and I went up to him and gave him $20 and told him to get me a cheeseburger and fries." While playing for the Red Sox, he was a part of the "Buffalo Heads", with Bill "Spaceman" Lee and Ferguson Jenkins. Carbo would also carry around a giant stuffed gorilla that was named Mighty Joe Young. The gorilla sat next to him in the middle seat on planes. Carl Yastrzemski wanted the gorilla placed on the bat rack in the dugout.