Justin Bieber has a new baby sister; see pictures of little Bay Bieber

Maria Puente | USA TODAY

Justin Bieber has a new sibling, half-sister Bay Bieber, born Thursday to Jeremy Bieber and his wife Chelsey.

Papa Bieber took to social media to announce the news and posted a picture of the baby, snug in a little knit cap, on Instagram.

"Just Welcomed a beautiful baby girl into the world. Bay Bieber #babygirl #biebergirl," Jeremy tweeted.

Just Welcomed a beautiful baby girl into the world. Bay Bieber #babygirl #biebergirl — Jeremy Bieber (@JeremyBieber) August 16, 2018

His Instagram picture showed him holding the baby as Chelsey grinned from a bed.

"We welcomed a healthy baby “Bay Bieber” born at 830 am," his caption read.

Justin Bieber was excited too; he posted his own picture of the baby on his Instagram page, a closeup of an adorable baby face.

"Meet the newest bieber, my little sister BAY BIEBER," he captioned it.

Jeremy, 43, and Chelsey, 30, married in February in the Caribbean, an event Jeremy documented on his Instagram page along with a picture of then-pregnant Chelsey.

She's been documenting her pregnancy on her own Instagram page, and posted her own photo of little Bay.

Bay 💕 A post shared by Chelsey Bieber (@chelseybieber) on Aug 16, 2018 at 10:01am PDT

Little Bay is the second child for Chelsey, who also has an 11-year-old daughter, Allie, and the fourth for Jeremy, including Jaxon, 8, Jazmyn, 10, and Justin, 24.

The global pop star is getting married himself, having proposed to Hailey Baldwin last month.

"Was gonna wait a while to say anything but word travels fast, listen plain and simple Hailey I am soooo in love with everything about you!" he wrote on Instagram, sharing two photos of Baldwin sitting on his lap and kissing his cheek.