O’Neill played Major League Baseball for 17 seasons, from 1985 to 2001. He appeared in six World Series and earned five World Series rings, one with the Cincinnati Reds and four with the New York Yankees. He also played in five All-Star games.

The Yankees honored him on August 21, 2022, by retiring his No. 21 during “Paul O’Neill Day” at Yankee Stadium.

O’Neill began his MLB career in 1985 with the Reds. After eight seasons with the Reds, O’Neill joined the Yankees in 1993, with whom he won the American League batting title in 1994 with a .359 average. From July 23, 1995, until May 7, 1997, O’Neill played 235 games in right field without making an error. In 1997, he led the American League in hitting with men on base with a .429 average. On Aug. 25, 2001, O’Neill became the oldest major leaguer to steal 20 bases and hit 20 home runs in the same season.

He was inducted into the New York State Baseball Hall of Fame in November 2017. In 2008, O’Neill was named “Father of the Year” by The National Father’s Day Council at its 67th Annual Father of the Year awards dinner in New York.