Nettles, 37, wore an Alexander McQueen gown for the intimate wedding, which took place near the Smoky Mountains in Tennessee. Nettles' Sugarland bandmate, Kristian Bush, was among the guests in attendance.
A former model, Miller appeared in the video for Sugarland's 2006 single, "Want To." The couple have been dating for more than two years.
Nettles is set to perform with Lady Gaga at the Grammy Nominations Concert Live, airing Wednesday at 10/9c on CBS, and will host the annual CMA Country Christmas special, airing Thursday at 9/8c on ABC.