The Murder On The Dancefloor hitmaker took to Twitter.com to announce the news in a cute online exchange with her partner.
Ellis-Bextor wrote on the microblogging site, "Hello all. Been finding it a bit nice-but-strange to be congratulated on a pregnancy I haven't actually announced yet..."
She then posted an image of her growing bump and directed a message to her husband's band The Feeling's Twitter page, asking, "What do you think, @thefeeling R? Is there a baby in there?" to which Jones replied, "Yes there is! Rx"
The singer then confirmed the news to her followers, writing, "Ah ok, cool! Mystery solved. Baby in autumn. Lovely! As you were. Xx"
The couple married in 2005 and share three sons.