He tweeted: "Myself and my wife @JodiWonderland are delighted to say we are expecting our first baby! We are so happy and cannot wait to be parents x."
Kian later added: "Thank you all so much for the lovely messages. We are so excited to be parents. Thanks for all the love and support x."
Jodi is part of girl group Wonderland, which was formed by Kian and his manager Louis Walsh after they held auditions for five female band members in 2008.
The 28-year-old beauty has taken to twitter to reassure fans the fivesome – who are also made up of Sharon Condon, Corrina Durran, Leigh Learmont and Kasey Smith - are not splitting up as a result of her pregnancy.
She tweeted: "For those worrying..Wonderland are not breaking up!That band means the world to me & the baby in my belly loves listening to my girls sing (sic).
"Thank you so much to everyone for all the excitement and congrats messages about our baby news... we can't wait! Love to you all xxx."