The season ended on a high note as UCLA overcame a 17-point fourth quarter deficit to beat rival USC in overtime, 48–41.

After an 0–2 start, UCLA won its remaining 10 games, including the 1998 Cotton Bowl Classic over Texas A&M, to finish Pac-10 co-champion and ranked No.

In his senior season in 1998, McNown led UCLA to a 10–2 record, including a Rose Bowl appearance as the sole Pac-10 champion.

With McNown at the helm, the Bruins' explosive offense carried them on a school-record 20-game winning streak from the previous year, as they won their first 10 games in 1998, before losing to Miami Hurricanes in their regular season finale in a loss that broke the 20-game winning streak and knocked UCLA out of the BCS Championship Game vs. Tennessee.

McNown set numerous school records in passing and offense, became the Pac-10's all-time career leader in total offense, and won a collection of post-season honors, including Pac-10 co-Offensive Player of the Year, the Pop Warner Memorial Trophy for best senior player on the West Coast, consensus first-team All-American honors and the Johnny Unitas Award as the top senior quarterback in college football.

In the 1999 Senior Bowl, McNown earned MVP honors as he threw two touchdowns in helping to lead the South team to victory.

McNown, along with Akili Smith, Daunte Culpepper, and Donovan McNabb, appeared on the cover of ESPN The Magazine in the issue highlighting the draft.

[5] In the months preceding draft day, the Bears had declared that Erik Kramer would be the starting quarterback, but waived him prior to signing McNown.

[5][6] Following the preseason, head coach Dick Jauron announced Shane Matthews would be the starter but that McNown would play at least one series every game to gain experience.

[6] McNown started his first game for the Bears on October 10 against the Philadelphia Eagles, taking over following a hamstring injury to Matthews the previous week.

[7] Early in a 14–13 win over the Green Bay Packers, he suffered a sprained right knee and was replaced by third-string quarterback Jim Miller.

[9] In the season-ending loss to the Tampa Bay Buccaneers, McNown threw 42 passes, which was the Bears' single-game rookie record before being snapped by Caleb Williams' 52 against the Indianapolis Colts in 2024.

[13][16][17] Following the loss to the 49ers that year, a Chicago Tribune report stated elements of the locker room were "in near revolt" over his performance, and his teammates made little effort to refute the story.

"[18] McNown's personality and drop down the depth chart behind Miller and Matthews prompted the Bears to trade him to the Miami Dolphins during the 2001 preseason.

Although he was initially competing against Tim Rattay, Giovanni Carmazzi, and Brandon Doman for the backup spot behind starter Jeff Garcia, McNown reinjured his shoulder during the preseason.

McNown was charged in September 1999 with the illegal possession of a disabled parking pass while playing football at UCLA in 1996,[21] to which he pleaded no contest.