The 20 singers chosen from nearly 350 applicants include three each from the United States and South Korea.
Swansea soprano Céline Forrest, 24, will represent Wales in June after winning the Welsh Singers Competition.
"Our final 20 are an exciting range of voice types, and an amazing array of talent," said artistic director David Jackson.
The eight-day event, which is held every two years, will run from 14-21 June and be broadcast extensively on BBC Four and BBC Radio 3, along with BBC Two Wales, BBC Radio Wales, BBC Radio Cymru, S4C and online.
A trio of judges flew for auditions in eight cities from Milan to New York to make the final choice of finalists from 55 countries.
"All of the singers we travelled to hear are, of course, equipped with fine voices and efficient techniques which alone will be their passport to a career in music," said producer Jeremy Caulton.
"What we were looking for in addition, however, is that indefinable something which makes one sit up and pay attention in a different sort of way."
The winner of the main prize will receive £15,000 and the Cardiff Trophy, while the Song Prize, awarded to the best singer of Lieder and art song, carries a £5,000 prize.
The rounds for the Song Prize will take place in the Dora Stoutzker concert hall at the Royal Welsh College of Music and Drama.
The line-up for this year's BBC Cardiff Singer of the World competition has been unveiled.