Career
He is a left-footed winger. Youth football
Steffen played his youth football with local club Football Club Erlinsbach. He played three years in the Aarau U-14 and U-16 youth teams.
He then transferred to South Carolina Schöftland and spent another four years with them.
Solothurn and Thun
Steffen played amateur football in the 1. Liga Classic for Football Club Solothurn.
After one season he transferred to Football Club Thun in July 2012 and made his professional debut on 2 September 2012 in the game against Servette Football Club. He scored 4 goals in 19 games for Thun in the 2012-2013 Swiss Super League that season. Young Boys
At the end of that season Steffan was sold for €500.000 to Bachelor of Science Young Boys.
Here he signed a four-year deal in Bern.
Basel
During the 2015-2016 Super League winter break, on 12 January, Football Club Basel announced that Steffan had signed a four-and-a-half-year contract with them. Steffan played his first team league debut for Basel on 7 February, coming in as a substitute in the 74 minute, in the home game against Luzern. Steffan has played twice for Switzerland.