He took his first serious musical steps in the mid-1970s when he took his first progressive rock band, Slowburn, into Jimi Hendrix's Electric Lady Studios in New York City.

He later credited Slowburn's initial failure as one of the luckiest things that could have happened to him, for it gave him the opportunity to learn the recording and concert business from the inside out.

[5] He landed a position at Leber-Krebs Inc., the management company that launched the careers of Aerosmith, AC/DC, Def Leppard, Ted Nugent, New York Dolls, Scorpions, Joan Jett and others.

It also introduced him to Jon Oliva,[11] Bob Kinkel and Al Pitrelli, as well as reconnecting him with studio engineer Dave Wittman, who all became original collaborators in O'Neill's next group, Trans-Siberian Orchestra.

The Hillsborough, Florida medical examiner's office determined the official cause of Paul O'Neill's death as accidental, resulting from an unexpected reaction to prescribed medications to treat his numerous chronic illnesses (including bone augmentation surgery, complications from spinal fusion surgery, heart disease, and hypertension).

[21] On June 24, 2017, TSO announced on their Facebook page that the band would continue the 2017 Winter Tour of "The Ghost of Christmas Eve" in O'Neill's legacy and honor.