On 17 March 2014, Bolshunov won the 20 km skiathlon event at the Russian Junior Nationals, resulting Bolshunov being bestowed the honorary Master of Sports of Russia. After the nationals he was invited to the junior team. A year later he participated in the sprint event of the FIS Junior World Ski Championships in Almaty, Kazakhstan, but failed to qualify for the sprint final, leaving him without medals. In the following Youth Championships in Rasnov, Romania, his best result was 2nd, in the relay event.