Having undergone successful cardiovascular surgery and treatment, Martínez participated in a full 2018 spring training and began the season as the Tigers' designated hitter. After struggling much of the 2018 season, Martínez stated on August 15 that 2018 would more than likely be his last in major league baseball. He said that he was just going to enjoy the last six weeks, and then go home to his cattle ranch in central Florida, where he now lives. The Cleveland Indians, where Martínez started his career and played for eight seasons, honored him before a game on September 15 in one of his last games in Cleveland before his announced retirement. The Tigers announced on September 19 that they would have a ceremony for him before the game on September 22. Martínez then announced that the game would be his final one so that he would take his last at-bat in front of his home crowd. After the pre-game ceremony, Martínez started the game at first base for the first time since 2016 at his request. He then beat out an infield single in his final at-bat in the bottom of the first inning, and was replaced with a pinch runner. As he walked off the field, he was greeted by teammates and two players from the Kansas City Royals gave him a hug.