The Premier League club headed into the January transfer window keen to bolster their frontline and quickly identified Malen, who can play up front or on either flank, as their number one target.
The Dutchman has just five goals in all competitions this season but has impressed in previous campaigns, finidng the back of the net 13 times in the Bundesliga last season.
This won't be the first time that he has plied his trade in England with the forward spending two years at Arsenal as a youth player before signing for PSV, where he broke into the first team and earned a €30 million move to Borussia Dortmund.