He played in Major League Baseball (MLB) for the Cincinnati Reds and Chicago White Sox during his 10-year career.

One of five children, his younger brother Denny O'Toole had a short major league baseball career.

[2] In 1958, the Reds assigned him to the minor league Nashville Vols, where he led the Double-A Southern Association in wins (20), innings pitched, strikeouts and bases on balls.

[9]) He pitched seven innings, giving up only one earned run on four hits, against a lineup that included future hall of famers Hank Aaron, Eddie Mathews, and Red Schoendienst.

[10][11][12][13][2] The Braves played their regular players to help pitcher Lew Burdette win his 20th game of the season.

[21] The Reds won the National League pennant in 1961, and met the Yankees in the 1961 World Series (losing 4–1).

[29] O'Toole later said that being selected as the starting pitcher by San Francisco Giants manager Alvin Dark was one of the proudest moments of his career.

[30] O'Toole played in Cincinnati until his final season, 1967, spent with his hometown team, the Chicago White Sox, but was ineffective due to arm troubles.

O'Toole tried to return with a 1969 expansion team, the Seattle Pilots, but was cut in spring training before the season began.

[32] After his baseball career ended, O'Toole had a successful second career in Cincinnati real estate sales and remained active in the community, supporting charities and participating in local events including the 2015 St. Patrick's Day parade where he served as the grand marshal.