[4][5] As the third-string quarterback behind Jake Plummer and Dave Brown, he appeared in a total of five games between the 1999 and 2000 seasons, while completing 7 of his 16 pass attempts for one touchdown and no interceptions.
In 2002, he was passed on the depth chart by rookies Josh McCown and Preston Parsons, leading to his release on September 1.
He shared the starting quarterback position with Nick Rolovich, playing most of the times in the second and fourth quarters of the games.
[8] He posted 76-of-131 completions for 843 yards, 10 touchdowns and 5 interceptions, while helping the team reach the World Bowl XI.
On August 25, 2009, Greisen signed with the Florida Tuskers for the inaugural season of the United Football League (UFL).
In the first round of the playoffs, the Iron beat the Chicago Rush to advance to the Arena Football League's conference championship, but lost to the eventual ArenaBowl champion Spokane Shock 60–57.
In the 2010 UFL Championship Game 20–23 loss against the Las Vegas Locomotives, he was 24-for-42 for 346 passing yards and two rushing touchdowns.
[10] On December 27, 2010, he was signed by the Dallas Cowboys' practice squad, to provide depth in case starting quarterback John Kitna could not play because of an oblique muscle injury.
[11] On December 31, he was promoted to the active roster for the season finale against the Philadelphia Eagles, in which he did not play as a backup to Stephen McGee.
[12] In 2011, Greisen returned to the UFL to play for the Virginia Destroyers, who assumed rights over the Tuskers' players when the team folded.
[13] In the shortened-season, Greisen led the Destroyers to a 3–1 record, with the one loss coming in the season finale against the Sacramento Mountain Lions in a game he sat out most of due to injury.
[15] On December 14, 2011, he was signed to the Cowboys practice squad after backup quarterback Jon Kitna was placed on the injured reserve list with a back injury.
He returned to the Destroyers for the 2012 season, which was cut short due to financial shortfalls; it was his last stint in professional football.
[21] He also runs the Chris Greisen Quarterback Academy during the season at Texas Stadium and through the offseason in Green Bay, Wisconsin.