Paul O'Neill's journey in Major League Baseball began when he was drafted by the Cincinnati Reds in the fourth round of the 1981 amateur draft. He made his major league debut with the Reds on September 3, 1985. O'Neill, a right fielder known for his strong arm and consistent hitting, quickly became a regular in the Reds' lineup. Over the next several years, he developed into a reliable player, contributing both offensively and defensively.

During his time with the Reds, O'Neill played a crucial role in their 1990 World Series championship team. That season, he batted .270 with 16 home runs and 78 RBIs, helping the Reds secure the National League pennant. In the World Series, the Reds faced the Oakland Athletics and swept them in four games. O'Neill's performance in the series was solid, and he was instrumental in the Reds' victory.

In November 1992, O'Neill was traded to the New York Yankees in exchange for Roberto Kelly. This trade marked a turning point in his career. With the Yankees, O'Neill's performance reached new heights. He became a fan favorite in New York, known for his fiery temperament and competitive spirit. His tenure with the Yankees coincided with one of the most successful periods in the franchise's history.

O'Neill's time with the Yankees was marked by numerous achievements. He was selected to the All-Star team five times (1991, 1994, 1995, 1997, and 1998) and won the American League batting title in 1994 with a .359 average. His ability to hit for both average and power made him a vital part of the Yankees' lineup. O'Neill's presence in right field was also a defensive asset, as he was known for his strong and accurate throwing arm.

The Yankees won four World Series titles during O'Neill's tenure with the team, in 1996, 1998, 1999, and 2000. His performance in the postseason was often clutch, and he delivered key hits in critical moments. O'Neill's leadership and intensity were highly valued by his teammates and coaches, and he became a symbol of the Yankees' success during the late 1990s.

O'Neill's final season in the majors was in 2001. He retired after the Yankees lost to the Arizona Diamondbacks in the World Series. Over his 17-year career, O'Neill compiled a .288 batting average, hit 281 home runs, and drove in 1,269 runs. His legacy in baseball is remembered for his competitive nature, consistent performance, and the integral role he played in the Yankees' dynasty years.

After retiring as a player, O'Neill transitioned to a career in broadcasting. He became a color commentator for the YES Network, where he provided analysis and insights into Yankees games.