The Big Reunion star popped the question to Rosanna underneath the Eiffel Tower and presented her with a diamond ring.
Antony had whisked Rosanna away to the French capital for her birthday but combined the trip with the surprise proposal. Aww!
After dental nurse Rosanna accepted, the happy couple posed for a picture together before Blue announced the news on their Facebook page.
In a message, a rep said: "It is with great pleasure we are pleased to announce the engagement of Antony Costa and his beautiful girlfriend Rosanna.
"Antony surprised Rosanna on her birthday today with a visit to Paris where he asked for her hand in marriage and she happily said yes.
"Everyone in Blue and the entire management team wish both Rosanna and Antony the very best for the future and we are all looking forward to the wedding."
Thankyou for your lovely messages myself and @RosannaJasmin are so happy to announce our engagement!!! Bring on 2014 xxx— Antony Costa (@AntonyCosta) December 23, 2013
After being inundated with messages of congratulations, Antony tweeted: "Thank you for your lovely messages myself and @RosannaJasmin are so happy to announce our engagement!!! Bring on 2014 xxx"
Rosanna also told her followers: "We're engaged!"
Antony will be the first Blue boy to walk down the aisle and we can't wait to see the wedding pictures. Will the rest of the band all be best men? We hope so!
More stars who are engaged to be married:
Copyright: Instagram Mark Wright