Knoll played for several youth teams from Berlin -Spandau, before he moved to the youth department of Hertha BSC in July 2004. In April 2007 he won the Poelchau high school, the discharged in Chile Football College World Series, where he faced the choice of South Africa scored one goal in a 2-1 victory in the final. The winning student selection belonged to, among other things Knolls Herthaner teammate Alfredo Morales, Fanol Perdedaj and Kevin Stephan.
In August 2008, Knoll played his first Regional game for the second team of Hertha BSC. In preparation for the 2010/11 season, he traveled for the first time with the pros in the summer training camp, but he could not play there in the squad. Nevertheless Knoll debuted on 5 December 2010 ( 15 Matchday) for Herthaer professional team in the 2nd Bundesliga, when he came off the bench in the 0-1 away defeat at TSV 1860 Munich in 69 minutes for Alfredo Morales. After he had risen with Hertha BSC in the 1st Bundesliga, Knoll was loaned to the beginning of the season 2011/12 for a year at the newly promoted second division Dynamo Dresden.
Then he made his debut on July 15, 2011 (1st Round ) for Dynamo as he stood in the 1:2 away defeat against Energie Cottbus in the starting lineup. His first competitive goal in Dynamo jersey Knoll scored 12 August 2011 (4th Round ) in a 4-0 win at home to 1.FC Union Berlin. For Dresden he made eleven games in the Bundesliga 2, in which he scored a goal. In 2012 he returned to Hertha. In the 2012/13 season, which ended with the rise in the Bundesliga for Hertha, Knoll came to six games and a goal.
For the 2013/14 season Knoll moved to SV Sandhausen, with whom he signed a contract until 30 June 2015. Previously, he had a contract with the MSV Duisburg closed, this had become invalid after license revocation for MSV.
Knoll played between 2006 and 2007 for the German U-17 national team, with whom he also took part in the U-17 European Championship 2007 in Belgium. Last Knoll in 2010 was captain of the trained by Frank Wormuth U -20 team.
- School champion in 2007 with the Poelchau High School
- Bundesliga promotion in 2011 with Hertha BSC
- Bundesliga promotion 2013 Hertha BSC