Colombo started his career at the famous youth rank of Atalanta. He made his debut on Serie B and for the club in 1998–99 season, and then joined Pistoiese. He was signed by the giant Internazionalein the summer of 2000 in co-ownership deal. He made his Serie A debut on 1 October 2000 against Reggina Calcio, and four other appearances at Coppa Italia, Italian Super Cup and the UEFA Cup match, in which he scored. In October, he was on loan to Torino Calcio along with Sixto Peralta, due to there being too many strikers on the squad. He failed to return to Inter, but was sold back to Atalanta, this time in the Serie A. His first ever Serie A season as regular was fair, in which he made 22 appearances.
Sampdoria and loans
In summer 2002, Sampdoria signed Colombo in a co-ownership deal, for 5.25 billion lire. He is one of the players who helped the club to be promoted, by playing 27 games. But his third Serie A season with his third Serie A club was bitter, he made just 2 appearances before the winter break. Colombo was loaned to Piacenza, Livorno and Ascoli, for exactly two seasons. The latter two were newcomers to the Serie A at that time, and Piacenza was also new to Serie B since being relegated. He returned to Sampdoria in January 2006, due to injuries of Emiliano Bonazzoli, when he made 12 appearances, without a goal.
In June 2006, Atalanta gave up the remain registration rights of Colombo to Sampdoria for free, while the "Blue-Black" also forced to sell Biagio Pagano to Sampdoria after no agreement was formed and a lower bid thereafter. But it saw Colombo sent to Brescia in a co-ownership deal on 29 August 2006, for a peppercorn fee of €500. Likes previous times, he failed to score regularly. On 29 January 2007, Spezia signed Colombo, from Brescia, with Sampdoria retained 50% registration rights, as an emergency signing. He finally scored regularly, scoring 8 goals in 18 games, which kept the place of Serie B for Spezia. He then transferred to Pisa Calcio in January 2008. Pisa paid €200,000 to Spezia to acquire its portion of registration rights. In June 2008 Sampdoria gave up the remain 50% registration rights to Pisa for free.
On 1 September 2008, he was signed by Bari in 2-year contract. On 31 August 2009, he signed a 2-year contract with Verona, after rule out from Bari first team. In August 2010 Colombo was released. Two days later Colombo was re-signed by Spezia.
