The pop veteran asked personal trainer Harley Rodriguez to marry him during a recent safari vacation in Africa, and shared the news with fans on Tuesday (15Nov16), when he appeared on satellite radio programme, The Jenny MCCarthy Show.
"We were in Africa, our parents were there - our mums were there - and I just figured this was the time to pop the question and make it official," Jonathan told host Jenny MCCarthy, who is married to his bandmate Donnie Wahlberg.
He went on to reveal they have "always considered ourselves a married couple", but he wanted to make their relationship official.
And Jonathan admits the setting was perfect for his surprise proposal.
"We were on the Zambezi river - it's right above Victoria Falls (between Zambia and Zimbabwe) - we took a night time raft dinner, just the four of us out on the river, there was like, a hippopotamus in the background," the singer recalled. "It was a super moon. It was just absolutely beautiful, it was so romantic."
The couple, which met in 2008, has yet to reveal when it plans to wed, but Jonathan and Harley will have to fit their big day around New Kids On The Block's new tour schedule after announcing plans on Tuesday for a joint trek with Boyz II Men and Paula Abdul.
The Total Package Tour kicks off in May (17) in Columbus, Ohio.
"Our fans know we love to bring them a party, and this tour is no exception," Wahlberg said in a statement. "It's not just a show, it's an experience. Paula Abdul is such a pop icon and Boyz II Men are one of the best R&B acts of all time. It's going to be a night of hit after hit, and we can't wait to deliver the 'Total Package' to our fans!"