The 21-year-old Dane spent the first half of this season playing for Heerenveen in the Dutch Eredivisie where he made 11 appearances and scored one goal.
Albion's technical director, Dan Ashworth explained, “This is an opportunity for Anders to play regularly with one of the biggest clubs in Denmark.
“He also has the opportunity of playing Europa League football during the second half of the season. It’s an excellent move for him, and we wish him all the best for the future.”
Dreyer joined Albion in August 2018 after helping Esjberg win promotion to the Danish top-flight with 18 goals in his first full season at senior level.
He played for Albion under-23s and spent the second half of last season in the Scottish Premier League with St Mirren, making 11 appearances and scoring one goal. He has also played at every age-group level for Denmark up to under-21s.
Under-23 coach Simon Rusk added, “Anders has been a pleasure to work with and on behalf of everyone connected with the club I wish him well for the future.”