Bratman, 26, proposed to the 23-year-old pop diva on Friday night while the two were vacationing at an undisclosed location, Prophet said.
"No wedding plans have been set yet," she said.
Bratman presented Aguilera with a diamond ring designed by jeweler Stephen Webster, she said.
The engagement initially was confirmed to the magazines People and US Weekly.
Aguilera, whose hits include "What a Girl Wants" and "Genie in a Bottle," won a Grammy as best new artist in 2000, another in 2002 for best pop collaboration with vocals for her cover of "Lady Marmalade" with Lil' Kim, Maya and Pink, and a third award last year for female pop vocal performance on "Beautiful."