The 20-year-old singer took home Denmark's second win at a Sweden-hosted Eurovision event, with a Danish singer earning a victory in 2000 at the contest held in Stockholm, TheLocal.se reported Sunday.
"This is totally fantastic," De Forest said. "I'm so happy."
Musicians from 26 countries participated in this year's Eurovision and viewers and professional juries from 39 countries voted to pick the winner.
The hometown favorite, Sweden's Robin Stjernberg, finished in 14th place, the website said.
With De Forest's win, Denmark is now responsible for hosting next year's Eurovision contest.