The 26-year-old has enjoyed a productive spell since signing for Freiburg in January 2016, scoring 18 goals in 47 competitive games. That total includes nine in 31 Bundesliga appearances this season, making him the club's joint-top scorer alongside Nils Petersen.
"I've received a lot of trust and a lot of playing time in the last year and a half here and I wanted to pay that back," said a delighted Niederlechner. "I feel at home at Freiburg and I look forward to scoring more goals with the team in the Bundesliga."
Born in Ebersberg, Bavaria, Niederlechner has also played for Unterhaching and Heidenheim. His first appearance as a fully-fledged Freiburg player will be on Sunday at home to Schalke.
Watch: Niederlechner notched a brace in Freiburg's win at Ingolstadt in December.