The Motley Crue rocker proposed to his model girlfriend during a romantic break to the island of St. Barts in the Caribbean.
He wrote on his Facebook page: "When Courtney and I were in St Barts I popped the question and she said YES ... We would like to thank everybody who has been tweeting and posting online us congratulations ... Both of us and our families are beyond happy. (sic)"
Nikki, 53, and Courtney, 27, have been dating since November 2010. She has previously joked about the difference in age between them, saying: "My dad and Nikki are the same age, so that was pretty funny. When I told my dad when we started dating, he was like, `Isn`t he the same age as me? Everything else has been really normal, but that`s the only thing that`s been a little awkward.
"Our lives are pretty mellow, he got everything out of his system, so we`re a pretty mellow couple, we go out to eat and we`re really homebodies."
`Girls Girls Girls` hitmaker Nikki has previously been married to former Playboy Playmate Brandi Brandt from 1989 to 1996 and actress Donna D`Errico from 1996 to 2007. He has children, Gunner, 21, Storm, 18, and Decker, 17, with Brandi, and daughter Frankie-Jean, 11, with Donna.