Knothe had joined the under-21 squad last summer from Eintracht Frankfurt but had been training with the first team since the restart and appeared in the squad for the first time in the play-off second leg against Ingolstadt.
Former coach Jens Keller had said the 21-year-old had made “a very good impression” whilst he has also impressed current under-21 coach Marek Mintal, who is a candidate for the vacant first team role.
The centre-back had one year left on his previous contract but his progress has been rewarded with a first team deal which will run until 2022. He is the second youngster to sign this summer, with Lukas Schleimer signing a professional deal last month.
“I am happy and proud to have this opportunity,” said Knothe on the club website. “It’s a nice feeling that the club has put their trust in me and believe in me.”
Defensive reinforcements will have been seen as necessary after a difficult season for Der Club, especially with Konstantinos Mavropanos leaving after a half-season loan from Arsenal. The Greek defender has now joined VfB Stuttgart.
Tobias Kraulich, Knothe’s defensive partner for the under-21s, has also left to join promoted Würzburger Kickers.
Meanwhile, the Nürnberger Nachrichten report on Friday that Osnabruck sporting director Benjamin Schmedes is a candidate for the role that will be vacated by Robert Palikuca at the end of the month. Dieter Hecking, previously coach of the club, has also been heavily linked with the job amongst many others.