Ünal has been playing in Spain since arriving at Villarreal from Manchester City in the summer of 2017.
Villarreal invested €14m in the young Turk, but he has spent the past two-and-a-half seasons out on loan.
Madrid club Getafe are now in advanced talks to take Ünal permanently from Villarreal, where he is not in the plans of new coach Unai Emery.
His move to Getafe is down to ‘clarifying the last details’, a source familiar with the situation disclosed.
The fee is not yet clear but a deal worth up to €8m has been under discussion, with a possible €5-6m base fee.
Villarreal wanted more but the economic crisis and Getafe’s limited budget has forced them to lower their price.
23-year-old Ünal has made 13 appearances for the Turkish national team since 2015, scoring twice.