The Romania under-21 international had previously agreed to join Albion in this window from FCV Farul last summer, and continued to play in Romania for the first half of the season.
Brighton & Hove Albion technical director David Weir said, “We have been monitoring Adrian and he has done well in Romania. He now has a new challenge with Vitesse in a new league and environment, and we will continue to track his progress closely.”
In total the 18-year-old winger made 46 appearances for FCV Farul, scoring nine goals and making four assists.