Johannes Strolz was born as the son of Olympic champion Hubert Strolz in Bludenz . After good performance at school level, the Warther moved to the main ski school in Schruns and later attended the Stams ski school, where he was accepted into the youth team of the ÖSV. After graduating from high school, he did the basic military service and completed training in the top sports team of the police.
After his European Cup debut in December 2011, Strolz took part in the Junior World Championship in Roccaraso in March 2012 , where he won the bronze medal in the Super-G . A year later he was classified in Québec in all five disciplines in the extended top field, but could not repeat the medal win. In the European Cup, he then concentrated increasingly on the technical disciplines and has so far achieved eight placements among the top ten. On December 8, 2017, he achieved his first victory in the Trysil giant slalom .
Strolz made his World Cup debut on December 14, 2013 in the giant slalom in Val-d'Isère . Since then he has only been used sporadically in the World Cup, but has not yet been able to win any points. In April 2016 he celebrated a prestigious success when he won the slalom in front of Fritz Dopfer and Dominik Stehle at the German Championships . A year later he was crowned Austrian champion for the first time in both giant slalom and slalom .
In January 2018 he won his first World Cup point in the giant slalom in Garmisch-Partenkirchen as 30th . His best placement of the season was 22nd in the giant slalom in Kranjska Gora in March. At the end of the 2017/18 season, he won the overall ranking of the European Cup. At the World Cup opener in Levi in November 2018, he won points in slalom for the first time as 15th. His best result for the time being was in February 2019 with twelfth place in the combination of Bansko . After a bad start to the season, he achieved his first top result in the night slalom in Madonna di Campiglio in January 2020 with tenth place.