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. He won the 2011/2012 championship and left the club. He was assisted by Matías Biscay, Pablo Rodríguez and professor Marcelo Tulbovitz during his time at Nacional Montevideo.
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.