Naglič, who started ski jumping at the SSK Alpina Žiri club at the age of seven in 1996 , first competed in FIS junior competitions in his hometown of Kranj in 2004. In 2006 he made his debut at the FIS jumping event in Eisenerz . After a 51st place there, a short time later he achieved good placements in both competitions in Einsiedeln with places eleven and fifteen. In July 2007 Naglič started in Bischofshofen in the FIS Cup , but could not convince with places 23 and 47. After further rather mediocre results in FIS jumping, he started in the Alpine Cup in September 2008, but also regularly missed top placements here.
After jumping into the top ten in the FIS Cup for the first time in January 2009, he got his first chance to compete in the Ski Jumping Continental Cup at the end of January in Titisee-Neustadt . In both competitions he missed the points with places 37 and 41. In the course of 2009 he was able to improve his performances in the junior area and in the FIS Cup and reached the podium several times. From the end of January 2010 he started firmly in the Continental Cup and reached the points from the first jumping in Iron Mountain . In the end he was able to occupy 91st place in the overall standings with 31 points.
At the start of the 2010/11 Continental Cup season , he achieved more points, so that on January 8th in Harrachov he was nominated for the first time for the qualification for a jumping in the ski jumping world cup . Surprisingly, he reached 22nd place in this qualification. In the two competitions he made the jump into the top 30 and thus into the second round. With places 26 and 23 he won his first World Cup points. A few weeks later he was back in the World Cup in ski flying in Oberstdorf , but missed the qualification. He also competed in ski flying in Vikersund . He managed to qualify, but missed the second round in both competitions and thus further World Cup points. At the end of the 2010/11 season he finished 62nd in the overall World Cup and 45th in the ski flying ranking. In the Continental Cup, he finished 49th with 129 points.
In the 2011 summer season , on July 31, he finished third in Courchevel, France, for the first time on the podium in a Continental Cup competition. A good year later he was able to achieve his first victory in this competition on August 10, 2012 in Kuopio, Finland .