Checchi took part in the Junior World Championships in Nordic skiing in 1999 and 2000. However, he could not place himself in the front field. His best result was a 30th place over the 10 kilometers in free technique in 2000. A year later, on December 8, 2001, he started in a World Cup competition for the first time . In his native Cogne he finished 71st out of 100 participants over the 10 kilometers in the classic technique. This season he won his first Continental Cup competition in Candanchú, Spain, over the 15 kilometers classic, which was held as a mass start.
The good results in the Continental Cup secured him a starting place in the Italian World Cup team in the 2002/03 season. So he succeeded on January 12, 2003 in Otepää, Estonia, for the first time to fight for World Cup points. In the mass start competition, he was 19th over 30 kilometers classic. Because of this result, he was able to start at the Nordic World Ski Championships in 2003 in the Italian Val di Fiemme (Fiemme Valley) in the pursuit competition and over the 30 kilometers classic, which were also held in the mass start. However, his best result was only 28th place over the 30 kilometers. He was the worst Italian starter in this competition.
In the 2003/04 season Checchi succeeded for the first time to place in the top ten in a World Cup competition. Over the 15 kilometers in the classic technique, he finished eighth in Kuusamo, Finland . At the Nordic World Ski Championships in Oberstdorf in 2005 , he was able to improve the results of the last world championship and was 24th in the pursuit competition and 18th over the 50 kilometers classic. In the following season, Checchi was able to further improve his performance and place himself in the top ten several times. In the overall World Cup he finished 29th for the first time in the red group. At the 2006 Winter Olympics in Pragelato , he achieved 38th place over 15 km classic and 18th place in the 30 km pursuit race.
In the 2006/07 season, Checchi's sporting career suffered a setback. Instead of moving closer to the top of the world, he rarely achieved a place in the points. At the Nordic World Ski Championships 2007 in Sapporo , Japan , his best result was 26th place in the pursuit competition. Over the 15 kilometers freestyle he was only 61st and over the 50 kilometers classic he finished the race prematurely. A year later, however, he managed to break through to the top of the world. In December 2007, he just missed the podium in fourth place over the 15 kilometer freestyle in Rybinsk, Russia . But he succeeded at the beginning of the Tour de Ski 2007/2008 when he was able to take third place in the pursuit competition over the 15 kilometers freestyle in Nové Město na Moravě . In the second pursuit competition in Nové Město he even came second behind his compatriot Pietro Piller Cottrer . In the overall ranking of the Tour de Ski, however, he only finished 15th, as he lost a lot of time on the fifth stage as 50th over the 15 kilometers classic. Strengthened by the success at the Tour de Ski, Checchi succeeded in winning his first World Cup competition in Canmore, Canada . He won the 15 kilometer freestyle on January 25, 2008 ahead of René Sommerfeldt . In the overall ranking of the cross-country skiing world cup, he finished tenth at the end of the season. In the overall ranking of the distance races, he finished sixth and placed 22nd for the first time in the overall ranking of the sprint competitions. At the beginning of the 2008/09 season he only achieved results outside of the World Cup points. He finished the Tour de Ski in 32nd place. At the following World Cup race in Whistler , he surprised with third place in the 30 km pursuit race. However, placements in midfield followed. At the Nordic World Ski Championships 2009 in Liberec he came in 24th place over 15 km classic, 21st place in the 30 km pursuit race and fourth place with the relay. At the Tour de Ski 2009/10 he came 14th overall. His best results at the 2010 Winter Olympics in Vancouver were 19th place over 15 km freestyle and ninth place with the relay. At the Nordic World Ski Championships in Oslo in 2011 , he reached 25th place in the 30 km pursuit race and fifth place with the relay. He finished 36th in the 50 km mass start race and 35th in the skiathlon at the 2013 Nordic World Ski Championships in Val di Fiemme . In the 2013/14 season he mainly competed in the Alpine Cup . In February 2014, he received a 14-month doping ban from the Comitato Olimpico Nazionale Italiano because he had provided incorrect or inadequate information about his whereabouts three times in the past 18 months.
Italy
Canmore
Candanchu
Pokljuka
Goms