Gary Shirley is officially a father of two.

'Teen Mom OG' Sneak Peek: Amber Portwood Learns Of Gary Shirley's Baby News

Last night, the Teen Mom OG star's longtime girlfriend, Kristina Anderson, gave birth to his second child, a baby girl. A short while later, the reality star took to Twitter, where he announced his exciting news to his many fans and followers.

"She's here!" Shirley tweeted at 8 p.m. on Thursday, April 30.

'Teen Mom' Star Gary Shirley Claims He'll Have Full Custody Of Leah 'Forever'

Shirley began dating Anderson shortly after his relationship with Amber Portwood, the mother of his 6-year-old daughter Leah, came to an end. Although Shirley and Portwood were once engaged, their engagement eventually came to an end, and Portwood later served a 17-month prison sentence after violating probation.

While Portwood was behind bars, Shirley moved on with Anderson, and the two announced they were expecting in fall of last year. Since then, they've been filming scenes for Teen Mom OG, which features the couple juggling their relationship with Shirley's co-parenting relationship with Portwood.

Although Portwood hasn't yet commented on Shirley's baby news, he spoke of his oldest daughter earlier this week, telling fans she was excited to meet her new little sister.

For more of Gary Shirley and Amber Portwood, tune into Teen Mom OG on Monday nights at 10 p.m. on MTV.

Tags: Gary Shirley teen mom teen mom og Kristina Anderson MTV Reality TV