Buckley, 34, proposed to his girlfriend, oncology nurse Abigail Ochse, on New Year's Eve in Hawaii, Us Weekly reports.
The actor popped the question in front of his mother, Ochse's sister and a group of the couple's closest friends while on vacation in Maui. He proposed under a tree in Turtle Bay at Napili Beach where the couple had left some of his late father's ashes the year before.
The ring was designed by Dan Wexler. The couple has been dating for two years.