Diamond had announced the engagement in September with a little rhyming post on Twitter: "Good news coming from sunny LA/and you're the first I want to tell/ Katie & I just got engaged/ and I hope you wish us well." He followed the announcement up by posting a photo of McNeil and wrote, "I'd like you to meet Katie. I'm lovestruck. I took this photo in London last month."
This will be the third marriage for the 71-year-old singer, who was inducted into the Rock and Roll Hall of Fame last year. It will be the first for McNeil, who is 42.
Diamond will be heading out on tour this summer, beginning in Fort Lauderdale, Florida on June 1st.