Neil's four older brothers played for local coaching legend Ted Monica and won state championships.

Coach Monica had retired by the time Neil enrolled at Madison High School, but mentored him throughout much of his young football life.

Coach Bobby Ross recruited him to the University of Maryland despite lacking the stats and honors of other high school stars.

The Krivak era was marked by mediocre results and the O'Donnell years featured an especially tough out-of-conference schedule.

The Terps finished 5–6 in 1988 and 3-7-1 in 1989, notably tying Penn State, only the second time Maryland had avoided losing to the Nittany Lions in the series up to that point.

In his first NFL start, O’Donnell completed 11 passes on 21 attempts for 152 yards and two touchdowns as the Steelers lost to the New York Giants 20-23.

[12] He finished the season throwing for 2,283 passing yards, 13 touchdowns, and 9 interceptions as he led the Steelers to an 11-5 record and took the AFC Central division title, but lost to the Buffalo Bills 24–3 in a divisional playoff game.

[13] In a Week 3 blowout victory over the division rival Cincinnati Bengals, O'Donnell completed 21-of-25 passes for 189 yards and three touchdowns to lead the Steelers to a final score of 34-7.

[15] On September 3, 1995, O'Donnell led the Steelers to a Week 1 win over the Detroit Lions, throwing seven completions on 10 attempts for 63 yards, but failed to score a touchdown.

O'Donnell would not make a regular season appearance until October 8's 16-20 loss to the expansion team Jacksonville Jaguars.

In the divisional playoff round, O'Donnell led the Steelers to a victory over the four time AFC Champions Buffalo Bills with a final score of 40-21.

Infamously, O'Donnell threw two nearly identical interceptions to Dallas Cowboys cornerback Larry Brown (with one apparently due to a missed route by Andre Hastings) that set up short touchdown drives in the second half.

[22] O'Donnell was not re-signed to the team following his Super Bowl performance, making him a free agent at the end of the season.

On February 29, 1996, he signed a 5-year $25 million contract with the New York Jets that was both more money than Pittsburgh but also close to his home in Madison, New Jersey.

On July 24, 1999, O'Donnell signed a multi-year contract with the Tennessee Titans, where he served as Steve McNair's backup.

Later, O'Donnell came off the bench and led Tennessee to a 47–36 victory over Pittsburgh in Week 17 en route to the AFC Championship and Super Bowl XXXIV, in which he was not an active participant.

O'Donnell retired after the 2002 season, but was talked into coming back for one game in December 2003 when McNair and Billy Volek were injured.

He started in the regular season finale and delivered a strong performance, completing 18 of 27 passes for 232 yards and two touchdowns, leading the Titans to a 33–13 victory over the Tampa Bay Buccaneers.

O'Donnell found work as a sports analyst, primarily covering the Titans at WTVF, Nashville's CBS affiliate (2005–2007).