The Mirror says an agreement is close, with the Bees willing to pay a fee rising to €30m, including bonuses (£25.56m).
Milambo, 21, will arrive just as the Bees are selling captain Christian Norgaard to Arsenal.
Negotiations between Brentford and Feyenoord have been ongoing for two months and manager Thomas Frank's departure for Tottenham hasn't altered plans.
Milambo was part of Holland's U21 Euros campaign and after defeat to England in the semifinals this week, he is now due at the Gtech stadium for a medical and to settle personal terms.
