Panettiere had previously said she was going to use the time off from Nashville to recover from her own post-partum depression.
A premiere date for Nashville Season 5 has not been announced.
CMT, in partnership with Hulu, picked up after ABC canceled the country music drama in May.
According to TVLine, Connie Britton and Hayden Panettiere are both set to return as the show moves to CMT, along with Charles Esten, Sam Palladio, Jonathan Jackson, Clare Bowen, Lennon Stella, Maisy Stella and Chris Carmack.