Phoebe added the hashtag, "Family Of Four."
Fans were quick to congratulate the pair.
"Congratulations to you all," one wrote.
"Great news," another added.
Phoebe and Sam already share daughter Poppy.
Congratulations!
Phoebe and Sam Burgess have welcomed their second child, a baby boy!
Taking to Instagram, Phoebe shared the happy news with fans.
"William “Billy” Mark Burgess. Born 9th December 2018, 4.22kg"
"Welcome to our world little big man, our hearts are so full."
Phoebe added the hashtag, "Family Of Four."
Fans were quick to congratulate the pair.
"Congratulations to you all," one wrote.
"Great news," another added.
Phoebe and Sam already share daughter Poppy.
Congratulations!