The 21-year-old German has completed a medical at Brentford and will become their first January signing.
Brentford have been keen to bring in potential cover for Ivan Toney, who could face a lengthy ban if he is found guilty of breaching FA betting rules.
Schade predominantly plays on the right wing but can also play as a centre forward.
A Germany Under-21 international who has scored once in eight Bundesliga appearances for Freiburg this season, Schade is viewed as an exciting prospect for the future.
He was clocked as one of the fastest players in Germany last season, with a top speed of 36.37km/h.
Brentford had a £17m bid for Schade rejected last summer but have stepped up their interest in a bid to strengthen their forward options.
Top scorer Toney has been charged with 262 FA betting offences. He was given until Wednesday, January 4 to respond to FA misconduct charges and faces a lengthy ban if found guilty.