Former LSU standout wide receiver/kick returner Skyler Green, a member of the Saints practice squad for most of the 2008 season, was also among the 19 players cut.
The departure of Harrington, who was sacked eight times in a 10-7 setback to the Miami Dolphins in the preseason finale on Thursday night, leaves the Saints with two quarterbacks on the roster - Drew Brees and Mark Brunell - for now.
Veteran tight end Billy Miller, who tore his right Achilles' tendon against the Dolphins, will be sidelined for the entire season after being put on injured reserve Saturday. Miller is expected to undergo surgery Monday.
The Saints also put rookie safety Chip Vaughn, a fourth-round draft pick, and fullback Olaniyi Sobomehin on IR.
Vaughn injured his left knee one week into training camp and did not play in any of the team's four exhibition games after having arthroscopic surgery on Aug. 11. Sobomehin suffered a shoulder injury against the Dolphins.
Also cut were guard Nate Bennett, tackle Michael Brown, center Digger Bujnoch, guard/tackle Anthony Davis, running backs Herb Donaldson and P.J. Hill, guard Tim Duckworth, cornerback Danny Gorrer, defensive tackle Earl Heyman, tight end Martrez Milner, tackle Jermey Parnell, defensive tackle DeMario Pressley, wide receiver Matt Simon and linebacker Anthony Waters.
The Saints kept defensive ends Will Smith and Charles Grant on the active roster even though they were expected to be suspended by the NFL for the first four games of the season.
Saints General Manager Mickey Loomis confirmed via e-mail Saturday night that the league has yet to announce their suspension, which could make them eligible for the Sept. 13 season opener with the Detroit Lions.
The Saints also traded a 2011 seventh-round draft pick to the New England Patriots for tight end David Thomas, a four-year veteran.
With Miller out and Darnell Dinkins hobbled by ankle and foot injuries since Aug. 14, the Saints had only two healthy tight ends in Jeremy Shockey and Buck Ortega.
Thomas, a 6-foot-3, 248-pounder, played in 32 games with 13 starts after joining the Patriots as a third-round draft choice in 2006.
He started 10 games last season when he caught nine passes for 93 yards, giving him 21 career receptions for 261 yards and one touchdown.
Starting today, the Saints can sign eight players to their practice squad. Several players who were cut Saturday could wind up on that unit if they clear 24-hour waivers this afternoon.
Other players who would be eligible for the practice squad are Arrington and Pressley, a fifth-round draft pick of the Saints in 2008, as well as Hill, Donaldson and Gorrer.
Saints by position
Quarterback (2): Drew Brees, Mark Brunell.
Running back (5): Reggie Bush, Pierre Thomas, Mike Bell, Lynell Hamilton, Heath Evans.
Wide receiver (5): Marques Colston, Devery Henderson, Lance Moore, Robert Meachem, Rod Harper.
Tight end (4): Jeremy Shockey, Buck Ortega, David Thomas, Darnell Dinkins.
Offensive line (9): Jammal Brown, Jon Stinchcomb, Jahri Evans, Carl Nicks, Jonathan Goodwin, Jamar Nesbit, Nick Leckey, Zach Strief, Jermon Bushrod.
Defensive line (8): Will Smith, Charles Grant, Sedrick Ellis, Kendrick Clancy, Bobby McCray, Jeff Charleston, Anthony Hargrove, Remi Ayodele.
Linebacker (7): Jonathan Vilma, Scott Fujita, Scott Shanle, Jo-Lonn Dunbar, Marvin Mitchell, Troy Evans, Jonathan Casillas.
Defensive back (10): Jabari Greer, Tracy Porter, Darren Sharper, Roman Harper, Malcolm Jenkins, Randall Gay, Leigh Torrence, Usama Young, Pierson Prioleau, Chris Reis.
Specialists (3): John Carney, Thomas Morstead, Jason Kyle.