The couple have been dating since last July.
An insider told E! Boller, 28, proposed to Prejean, 22, during the weekend in Prejean's hometown of San Diego. No other details about the happy occasion were immediately reported.
Prejean sparked controversy last year when she answered a question about gay marriage during the Miss USA pageant by saying she believes marriage should be defined as the legal union of a man and a woman.
Pageant organizers later stripped her of her Miss California title, stating she did not live up to her obligations. Prejean has maintained it was her conservative views that led to her ousting.