Johannessen played for the national team and represented Norway at the
2012 Eisenhower Trophy with Anders Engell and
Kristoffer Ventura, where they finished sixth. He also played on the winning side in the 2010
Jacques Léglise Trophy, where Continental Europe won. He played in the
European Boys' Team Championship three times and won silver in 2010, after he was beaten by
Thomas Pieters of Belgium by 3 to 2 in the final. He had his international breakthrough at 19 during the qualification for the
2014 Open Championship, where he lowered the course record at
Bruntsfield Links near
Edinburgh by four strokes, from 67 to 63 (eight under par). In January 2015 Johannessen was slated to move to the U.S. to play college golf with the
Tennessee Volunteers men's golf team at
University of Tennessee, but decided to turn professional. ==Professional career==