The French Open runner-up is the top seed for the inaugural staging of the WTA International clay-court event and raised few eyebrows with a comfortable progression past world number 190 De Vroome - only in the tournament due to the withdrawal of Kristina Mladenovic.
Aside from having to survive three break points at 2-0 up in the first, Halep faced little resistance as she dominated the opening set to the delight of home fans.
The second was a little more hotly contested, with Halep having to outnumber her opponent by three breaks to two to book her place in the last 16.
Compatriot Alexandra Dulgheru had less success against second seed Roberta Vinci as she was dumped out of the tournament 6-2 6-3.
In the day's remaining first-round match, qualifier Kiki Bertens defeated Irinia-Camelia Begu 6-0 3-6 6-2.
While the top seeds were getting their campaigns under way, others were already celebrating their place in the quarter-finals.
Home favourite Monica Niculescu gave the crowd plenty to cheer as she won 63 per cent of the points on her own serve on the way to a 7-5 7-5 win over Elitsa Kostova.
However, another player from the host nation - world number 228 Cristina Dinu - saw her campaign ended by Kristina Kucova in a 2-6 3-6 defeat, while eighth seed Polona Hercog battled to a 6-2 5-7 7-6 (7-4) triumph over Poland's Katarzyna Piter.
The only other second-round match of the day saw Lara Arruabarrena Vecino of Spain beat Turkey's Cagla Buyukakcay 7-5 3-6 7-6 (8-6).