Russia's Katya Jones, Spain's Gorka Marquez and Ukraine's Oksana Platero said they felt "privileged", "excited" and "fortunate" to be taking part.
They and unconfirmed others will step in for Ola Jordan, Tristan MacManus, Kristina Rihanoff and Gleb Savchenko.
Aliona Vilani, who won last year's show with Jay McGuinness, is also departing.
Platero previously appeared on Strictly's US sister show Dancing with the Stars, where she danced for five seasons as Oksana Dmytrenko.
She also worked as a choreographer on US TV show So You Think You Can Dance, going on to marry one-time contestant Jonathan Platero.
Born Ekaterina Sokolova in St Petersburg, Katya Jones is the wife and partner of British dancer Neil Jones, one of Strictly's choreographers.
She and Neil have won the World Amateur Latin Championships three times and became the World Professional Latin Showdance champions last year.
Gorka Marquez represented Spain at the World Latin Championships in 2010 and has toured internationally with stage show Burn the Floor.
Returning dancers this year include Anton du Beke, Brendan Cole and the husband and wife team of Kevin and Karen Clifton.
Russian dancer Savchenko, who appeared on last year's show as the partner of TV presenter Anita Rani, said he was leaving Strictly "due to family commitments".
Louise Rainbow, Strictly's executive producer, said she was "delighted" with this year's professional dancer line-up and was looking forward to "another brilliant and entertaining series".
According to the BBC, more professional dancers "will be announced in due course".
Three new performers will join Strictly Come Dancing's line-up of professional dancers when the BBC One ratings winner returns in the autumn.