According to Figueredo, the 1923/24 Leopardos are "considered as the most dominant team ever in the history of Cuban baseball." Dibut appeared in nine games with a 3–3 record. That winter the Cincinnati Reds signed Dibut as a free agent. Dibut made his major league debut on May 1 against the Chicago Cubs, entering in the seventh with the Reds behind 8 to 1. He pitched the last two innings without giving up a run, allowing only one hit. After one appearance, Dibut was assigned to the Bridgeport Bears of the Eastern League. In late June, he was reassigned to the St. Petersburg Saints of the Florida State League. He went 8–2 with the Saints and allowed only 13 runs in 75 innings pitched. In August Dibut was recalled by the Cincinnati Reds and on August 17 he appeared in his second major league game. He entered in the top of the fifth inning against Brooklyn with the Reds behind 8 to 3, and pitched five shutout innings without giving up a hit. The final score was 8 to 5. He made his first major league start a week later against Boston and pitched a complete game, holding the Braves to two runs on four hits in an 8–2 victory for the Reds. Dibut finished the 1924 season with a 3–0 record in seven major league games—two complete game starts and five relief appearances. His earned run average was 2.21 in innings pitched. At the end of the season, he was offered a contract for the following year which stipulated that he was not allowed to play winter ball in Cuba. In the spring of 1925, Dibut reported late to spring training because of difficulties in obtaining a passport. It was reported that the problems were due to a felony conviction several years earlier in Cuba. Dibut developed a sore arm in spring training in Orlando, but remained on the Reds' roster when the season started. His only appearance in 1925 occurred on April 22 against the St. Louis Cardinals. He came into the game in the bottom of the first with two outs, two runners on base, and the Reds already behind 7 to 2. He proceeded to give up consecutive hits to Rogers Hornsby, Jim Bottomley, and Les Bell, allowing four more runs to score. Harry Biemiller was called in to relieve Dibut before he'd recorded any outs. On May 6, manager Jack Hendricks announced that the Reds had unconditionally released Dibut. In the spring of 1926, Dibut returned to the St. Petersburg Saints, saying that he hoped to return to Cincinnati.