The couple will get married in the summer of 2015, but the specific date is still to be decided, according to a statement published on the Royal Court's website.
Carl Philip, 35, is the only son of the royal couple.
His two sisters, Crown Princess Victoria and Princess Madeleine, are both married and have a daughter each.
Hellqvist, 29, became famous for participating in a reality show before meeting the prince. She has devoted recent years to a non-profit she founded with a friend to help children in South Africa.
"I received the ring this morning," Hellqvist said during a press conference in the gardens of the royal palace.
The couple has been together for four years.
The Swedish monarchy's popularity has fallen in recent years amid a series of scandals surrounding the king, but a majority are still in favour of the institution.
