Jansen grew up in Orange City, Iowa, and played high school ball at MOC-Floyd Valley. He joined the Augustana University Vikings in 2012. In 2016, he was named the Northern Sun Intercollegiate Conference Player of the Year, and also NCAA Division II national player of the year.
After graduating from Augustana in 2016, he signed with Limburg United of the Belgium Division I. In 33 regular season games Jansen averaged 9.2 points and 3.4 rebounds per game, while bumping his scoring output up to 17.3 points in the playoffs.
On 18 August, 2017, he signed with Macedonian basketball club MZT Skopje. He made his debut for MZT Skopje in their season opener on September 29, 2017, scoring 14 points, three rebounds and one assist in a 92–89 win over the Partizan. On 27 October, 2017, he left MZT Skopje.
