Pellegrino had his first international appearance at the Junior World Championship 2009 in Praz de Lys Sommand, where his best result was the 25th place in the sprint competition. The following year he won the bronze medal in the sprint competition at the Nordic Junior World Championships 2010 in Hinterzarten behind the Norwegians Tomas Northug and Pål Golberg . After winning the Slavic Cup , he was nominated for his first appearance in the cross-country skiing world cup . In the sprint in Drammen , however, he failed in qualifying. But just three days later he won his first World Cup points in Oslo with 19th place. Since the 2010/11 season , Pellegrino has regularly competed in sprint competitions in the World Cup. After clearly missing the qualification for the finals in Düsseldorf , he surprised in Davos with the fastest qualifying time. He reached the finals and celebrated his first top ten result with sixth place. But already on his next appearance at the World Cup in Liberec he reached the finals again and only had to admit defeat to the Norwegian Ola Vigen Hattestad . At the following Nordic World Ski Championships in Oslo in 2011 he was 12th in the sprint. In the following season he reached the top ten several times in sprint races.
In the Tour de Ski 2012/13 , which he did not finish, Pellegrino finished second in the sprint stage in Val Müstair . At the U23 World Championships in Liberec , he won gold in the sprint. He achieved 12th place in the sprint and fifth place in the team sprint at the Nordic World Ski Championships in 2013 in Val di Fiemme . In the 2013/14 season he came second in the sprint stage of the Tour de Ski 2013/14 in Oberstdorf and in the World Cup sprint race in Nove Mesto . At the 2014 Winter Olympics in Sochi , he finished 11th in the sprint and team sprint. In the 2014/15 season he won his first Sprint World Cup victory in Davos in December 2014 . A third place in the team sprint in Otepää and another victory in the sprint in Rybinsk followed . At the Tour de Ski 2015 he won the sprint stage in Val Müstair. At the Nordic World Ski Championships in Falun in 2015 , he finished sixth in the relay and fifth in the sprint. Together with Dietmar Nöckler he won bronze in the team sprint. He finished the season in 14th place in the overall World Cup and third in the Sprint World Cup. At the Rollerski World Championships 2015 in Val di Fiemme , he won the bronze medal in the 25 km mass start race and the silver medal in the team sprint together with Dietmar Nöckler. After finishing 22nd at the Nordic Opening in Ruka at the beginning of the 2015/16 season, he won the freestyle sprints in Davos and Toblach . At the Tour de Ski 2016 , which he ended prematurely, he won the sprint stage in Lenzerheide . At the following World Cup in Planica he won the sprint and the day after that he won the team sprint together with Dietmar Nöckler. In Nové Město he was third with the relay. At the end of the season he achieved 31st place in the Ski Tour Canada . He won the sprint in Canmore . He finished 16th in the overall World Cup and won the Sprint World Cup. At the beginning of the 2016/17 season he came 39th in the World Cup mini tour in Lillehammer . At the Tour de Ski 2016/17 , which he ended prematurely, he came second in the sprint stage in Val Müstair. In January 2017 he won the sprint in Falun and together with Dietmar Nöckler took third place in the team sprint in Toblach. At the season highlight, the Nordic World Ski Championships 2017 in Lahti , he won the silver medal together with Dietmar Nöckler in the team sprint and the gold medal in the sprint. He was also eighth with the relay. At the end of the season he came in 19th place at the World Cup finals in Québec and reached 22nd place in the overall World Cup and second place in the Sprint World Cup.
After 21st place in the Ruka Triple at the beginning of the 2017/18 season, Pellegrino was second in the sprint in Lenzerheide and won the sprint in Dresden and, together with Dietmar Nöckler, in the team sprint. At the 2018 Winter Olympics in Pyeongchang , he won the silver medal in the sprint. He also achieved seventh place in the relay and fifth place in the team sprint. In March 2018, he triumphed in the sprint in Lahti and took second place in the sprint stage of the World Cup final in Falun , which he finished in 19th place. Finally, he achieved tenth place in the overall World Cup and second place in the Sprint World Cup. At the beginning of the 2018/19 season he won the sprint in Lillehammer and took 44th place in the Lillehammer Triple. In Davos he finished second in the sprint. At the Tour de Ski 2018/19 , which he ended prematurely, he also came second in the sprint in Val Müstair . In February 2019 he triumphed in the sprint in Cogne and took second place in the sprint in Lahti. At the season highlight, the Nordic World Ski Championships 2019 in Seefeld in Tyrol , he and Francesco De Fabiani won the bronze medal in the team sprint and the silver medal in the sprint. At the end of the season he ran at the World Cup finals in Québec with second place in the sprint, sixth place and finally reached eighth place in the overall World Cup and second place in the Sprint World Cup. The following season he finished 19th in the Ruka Triple and came second in the sprint in Planica , Lenzerheide and Åre . He finished 16th in the overall World Cup and fourth in the Sprint World Cup.