The couple's new arrival was announced on Seven Network breakfast programme The Morning Show by hosts Kylie Gillies and Larry Emdur on Thursday morning (May 10).
"It is with much joy and pride that Jessica Marais and James Stewart announce the birth of their baby girl, Scout Edie Stewart," read a short statement released by the couple's management team.
No further details about the birth have yet been made available.
It was recently reported that Stewart will leave Seven drama Packed to the Rafters and that any return is uncertain as he prepares to help raise his new daughter.
The couple plan to return to the US next month, as Marais is a cast regular on Starz drama Magic City.
Ryan Corr - Marais's former co-star on the Seven Network drama - recently said that Marais was "completely relaxed", yet "so excited" ahead of the birth.
He also said that he thought the couple would "make the most down-to-earth, wonderful parents".