Mr Marvelly said it had been a privilege to own and operate the hotel.
"Having the opportunity to create experiences for guests, and making people's days and nights special has been a pleasure."
The hotel has around 30,000 guests staying every year, with about 50,000 guests dining in the restaurant. It has hosted a number of concerts including Dame Malvina Major, the late Sir Howard Morrison, Carl Doy, Greg Johnson and John Rowles, while the Marvellys' singer-songwriter daughter Lizzie cut her teeth performing in the restaurant as a teenager.
"It is extremely satisfying knowing that Vlasta and I have always given our best, with our motivation being guest satisfaction," Mr Marvelly said.
"Thirty years is a long time, realising that a hotel never closes its doors. It gives true meaning to 24/7. A normal working week for us would be around 80 hours so it's time to say goodbye."
He said they wanted to thank those who had helped them over the years.
The couple have no plans to leave the district and Mr Marvelly will remain on the Rotorua West Rotary Club and Destination Rotorua Board.
"To Rotorua, we believe we have left a legacy for future generations to appreciate the history and charm that the Princes Gate Hotel offers," Mr Marvelly said.
Lizzie Marvelly, who now lives in Auckland, said she was "extremely proud" of what her parents had achieved.
"They've poured their hearts and souls into the Princes Gate Hotel over the past 30 years. I've never met anyone who works harder than my parents. I'm thrilled that they will now have time to kick back a little - although I suspect slowing down will not be on the agenda."
The new owners will take over on April 26.