Matías Donnet (born April 18, 1980 in Esperanza, Santa Fe) is an Argentine football (soccer) midfielder, who last played for Unión de Santa Fe.
With Boca Juniors he won the Intercontinental Cup 2003, the Copa Libertadores de América 2003, and the Copa Sudamericana 2004 . At the match for the Intercontinental Cup, Donnet scored the equalizer that took the match to penalty shootout, won by Boca 3–1, and was named Man of the Match.
In 2006 he signed with D.C. United of Major League Soccer in the USA. He scored his first and only goal in the MLS on September 26, 2006 against New York Red Bulls. The goal was scored in the 89th minute and turned out to have been the game winner when Red Bull's Jozy Altidore scored to make the score 4–3 United.
Donnet left D.C. United after the 2006 season and returned to Argentina with Belgrano de Córdoba. Between 2007 and 2009 he played for Newell's Old Boys before returning to his first club Unión de Santa Fe. In summer 2014, Donnet signed with Antigua GFC of the Guatemalan Liga Mayor for one year. He is currently one of their top players in the clausura 2015 season.