The MTV reality star announced via Twitter that she'd welcomed her second child on Friday, 29 May.
She weighed 7lbz 15oz.
Proud mum Maci gushed: "She is beautiful and as healthy as can be!"
She later added: "Laying here at 2am with my beautiful baby girl... thinking abt how completely in love i am with Taylor and my two amazing children. #blessed."
Jayde is Maci's first child with boyfriend Taylor McKinney. She's also mum to son Bentley, six, from her relationship with ex-boyfriend Ryan Edwards.
The family can currently be seen in MTV's new show Teen Mom OG, which catches up with original stars Maci, Amber Portwood, Farrah Abraham and Catelynn Lovell.
Maci and Taylor announced the pregnancy in December and revealed in March they'd already decided to name their daughter Jayde.
Speaking to People recently, Maci said: "We definitely want to get married and we've talked about it a lot. But we aren't trying to cram it all in at one time. After the baby comes and we get settled in with parenting two children, then that will definitely be our next step."