[1] On March 26, 2012, the Winnipeg Jets of the National Hockey League (NHL) signed O'Neill to a three-year, entry-level contract.

[4] In the 2016–17 season, O'Neill spent the entirety of the year with AHL affiliate, the Lehigh Valley Phantoms, recording 28 assists and 31 points in 57 games.

During his second year under contract with the Flyers in the 2017–18 season, O'Neill was recalled from the Phantoms and belatedly made his NHL debut against the St. Louis Blues at the Scottrade Center on November 2, 2017.

[6] In the following 2018–19 season, O'Neill was unable to recapture his previous success in Wilkes/Barre/Scranton, limited to 8 assists in 28 games from the blueline before opting to be released from his contract with the club on January 25, 2019.

[7] O'Neill decided to continue his career abroad, promptly agreeing to his first European contract in signing for the remainder of the season with Austrian club, EC Red Bull Salzburg of the EBEL, on January 29, 2019.