Tina Douglas told a Manhattan jury on Thursday that Devar Hurd sent her a series of profane and threatening voice mails and text messages.
She said some of the messages described how he wanted to have sex with the Grammy-winning singer.
Hurd, a gym worker from Indiana, was arrested earlier this year on charges of stalking and harassment. His lawyer said he meant no harm.
Ashanti was raised in Glen Cove, N.Y. The multiplatinum-selling singer got her first record deal at 14; her hits include "Foolish" and "Only U." She has appeared in films including "Coach Carter" and "John Tucker Must Die."