The Kings Of Leon rocker and his supermodel wife - who tied the knot in May after dating for more than two years - confirmed they are "thrilled" to be welcoming a new addition into their family.
Speaking in a statement, the couple said: "We are thrilled to announce that we are expecting our first child together. We can't wait to meet the new addition to our family."
Meanwhile, Caleb's brother and Kings of Leon bandmate Jared Followill has expressed his delight at hearing he is to become an uncle.
Writing on his twitter page, he said: "So excited to be an uncle! Congrats Caleb & Lily! If it's a boy, we gonna be hitting da club together every night! If it's a girl....church. (sic)"
After Caleb and Lily tied the knot earlier this year, the 'Someone Like You' hitmaker admitted he was eager to start a family with the 26-year-old beauty.
He said: "I can't wait to raise a family with her because she's a great woman."