The 19-year-old Dane has made nine Championship appearances this season.
He scored his first career goal in the 2-0 win at Nottingham Forest in February.
Town boss David Wagner told the club website: "We are proud he is our player. He has taken his opportunity in the team recently, showing he can bring his performance to the pitch."
Huddersfield Town midfielder Philip Billing has signed a contract extension until the end of the 2019-20 season.