As a 17-year-old Hossler briefly held the lead during the second round of the 2012 U.S. Open at The Olympic Club before settling for a share of 29th. This will be his fourth U.S. Open start, but first as a professional. He also made the cut in 2015 while a standout at the University of Texas, and missed the cut as a 16-year-old at Congressional in 2011. He qualified at Springfield (Ohio) Country Club, shooting 5-under 135. He turned professional in 2016 with one year of eligibility remaining at Texas. He is still seeking his first professional victory. He was the stroke-play medalist in the 2011 U.S. Junior Amateur, losing in the quarterfinals. In 2014, he won the Western Amateur and he claimed the 2016 Jones Cup Invitational. Hossler was a member of the 2015 USA Walker Cup Team and the victorious 2014 World Amateur Team. He also represented the USA in the 2012 Junior Ryder Cup and 2015 Palmer Cup.