Giudici was given the final rose -- and a proposal -- during a dramatic ceremony in Thailand.
The 26-year-old graphic designer accepted the proposal, and the couple has already said they want to get married as soon as possible.
The ceremony will be televised on ABC, but a date has not been set.
The network also announced on Tuesday that Lowe is headed to "Dancing with the Stars."
Lowe will be competing for the disco-ball trophy when the show returns for its 16th season. He will partner with Peta Murgatroyd.