The singer was reportedly at her side for the birth.
PEOPLE also confirmed the news, and said the new parents had called their baby boy "perfect".
They reported a source close to the couple said: "Louis Tomlinson and Briana Jungwirth welcomed their first child, a son, this week in Los Angeles."
On 22 January, before it had been confirmed, One Direction fans were in a frenzy after a fan account claimed Jungwirth had given birth.
The fan account @1DExclusiveInfo claimed Briana’s own grandmother had confirmed the news.
Liam has been in LA since Thursday night— . (@1DExclusiveInfo) January 10, 2016
Briana's grandmother confirmed that the baby is a boy— . (@1DExclusiveInfo) January 22, 2016
Tomlinson has not yet confirmed the birth, however people are using the hashtag #WelcomeBabyTomlinson with congratulations messages.
And that's not all - people are already betting on the name.
Novelties Trader for Betfair, Colm Rock, said: "It seems Betfair customers aren’t quite convinced that the baby will be called Jacob which is 6/1, with a majority backing Leo at 11/2 favourite.
"The boys' names are certainly leading the charge with Johannah, Louis’ mother’s name one of the few girls name to appear at the top of the market at 8/1.
"Louis said he’d love to call the baby Lucas in a recent interview for Top of the Pops Magazine which is seeing some interest at 9/1."
It was revealed in July that the singer was expecting his first child with Jungwirth.
A mutual friend told PEOPLE at the time: "Louis is happy and very excited about becoming a dad and he thinks Briana will be an amazing mother."