The couple - who announced they were expanding their family just days after his brother and fellow band mate Caleb Followill welcomed his daughter Dixie Pearl with wife Lily Aldridge last summer - had a baby daughter Violet Marlowe Followill on Wednesday (26.12.12) in Nashville.
A spokesperson for the 33-year-old rocker confirmed the news to People.com, saying: ''Mom, Dad and baby are doing well and are so in love!''
The baby girl was born at 4.01pm, weighing 7lbs, 13 oz.
Writing on twitter shortly before the birth, Nathan said: ''I'm beyond excited/anxious.''
The couple tied the knot in November 2009.
Nathan is the third member of the popular band to have a child; his cousin Matthew Followill and his wife Johanna Bennett welcomed their son Knox Cameron Patrick Followill in April 2011.
Kings of Leon - known for songs including 'Sex On Fire' and 'Use Somebody' - are currently on a hiatus following their tour of Australia last November, and Nathan had most recently been supporting his singer/songwriter wife while she toured with her album 'Little Spark'.