The UFC superstar just revealed she's engaged to her UFC fighter boyfriend, Travis Browne -- who she's been dating since 2015.

Browne popped the question with a massive diamond ring -- and said he proposed under a waterfall in New Zealand about a week ago because "it felt like the right place to do it."

Ronda says she hopes the wedding will be soon -- but says she also doesn't know what goes into planning a wedding ... so, she's keeping an open mind about the date.

Congrats!!!

We reached out Dana White who says, "I'm very happy for Ronda and I'm looking forward to the wedding!"