The Sugarland singer, who is currently appearing as a mentor on ABC's talent contest Duets, married her husband Justin Miller last November.
Sugarland's manager Gail Gellman has now told People that Nettles is pregnant.
"They are thrilled beyond belief," Gellman added.
Nettles is said to be due to give birth to her baby in November.
Duets continues Wednesday on ABC.
Watch Jennifer Nettles perform on Duets below: