He was supposed to play on the 2013 U.S. Men’s Junior National Team but got called up to the senior team instead. He debuted with the U.S. national team at the NORCECA Championship, which USA won; Christenson was named "Best Server" and "Best Setter" in this tournament. He also competed in the 2013 FIVB World Grand Champions Cup. In 2014 he won the gold medal at the World League, held in Florence, Italy. He began senior-level competition at age 20. He is the youngest starting setter to ever compete for the U.S. on a national team for both junior level and senior level.