However in his third season, things did not go well off the pitch for Gallardo as he was not in good terms with his coach Didier Deschamps after being named on the bench midway through 2000-01 season. Following the examples of Panucci and Simone, Gallardo decided to leave Monaco at the end of the season.
Marcello Gallardo was bought by the Parisian club PSG for an undisclosed fee in January 2007. Paris Saint-Germain signed a two year contract with Marcelo and made his debut in a 3-0 cup win against Nîmes on 7 January.
On 13 January 2007 he played his first Ligue 1 match for PSG against Valenciennes
After spending only one season with the club, Gallardo terminated his contract, looking to move to Major League Soccer in the United States.
On 29 January 2008 Gallardo was presented as the newest member of D.C. United. With a 2008 salary of $1.87 million, Gallardo is the highest-paid player in United history and its first Designated Player. Gallardo has the third-largest salary in MLS for 2008, behind English midfielder David Beckham of the Los Angeles Galaxy ($6.5 million guaranteed) and Mexican forward Cuauhtémoc Blanco of the Chicago Fire ($2.67 million). He scored his first league goal for United on 5 April 2008 against Toronto FC. On 17 and 19 July Gallardo underwent surgery for a sports hernia. In February 2009 he left D.C. United and returned for the third time to his old club River Plate.
In 2010 he signed at Nacional de Montevideo in the Uruguayan League. On 12 June 2011, Gallardo played his last match winning the Uruguay Tournament making him one of the few players to win a championship or a league in every team that he played. He retired as a player, and was hired a few days later as new manager of Nacional, his first job as a football manager.
Gallardo's style of play was widely lauded by the Argentine press, with the team matching the club's all-time unbeaten record on November 9th with 32 undefeated games, losing to Estudiantes de La Plata three days later. Out of the 32 games, 8 belonged to Ramón Díaz's tenure. River Plate led the Torneo de Transición for the better part, until Gallardo's team reached the Copa Sudamericana's semi-finals, where River would face rivals Boca Juniors. Planning to rest the players for the semi-finals, Gallardo played a substitute team against second-placed Racing Club, ultimately losing the match from an own goal by Ramiro Funes Mori. Racing would go on to win its first championship since 2001 by two points over River Plate.
River eliminated Boca with a lone goal from Leonardo Pisculichi in the second leg played at the Monumental. In the 2014 Copa Sudamericana Finals, Pisculichi scored once again to draw 1-1 against Atlético Nacional in the away leg at the Estadio Atanasio Girardot. Defenders Gabriel Mercado and Germán Pezzella, in the span of four minutes, scored with headers in the second leg at the Monumental, giving River Plate a 2-0 win and its first international title since 1997, remaining unbeaten in the competition. Marcelo Gallardo became the first River Plate player to win an international title both as a player and a coach. Following the end of the game, Gallardo dedicated the win to his mother, who had passed away shortly before the second game against Boca Juniors.
He tended to play as a central playmaker. He is well known for his free kicks and corners, and he is also skillful in confrontation and possesses an intelligent footballing brain, although he is best known for his defense splitting passes.