"Hello! can exclusively announce the safe arrival of @MrJackO & @lisamarstelly 's baby girl Pearl weighing 8lb 6oz. Love & congrats to them!" the magazine said in a Twitter posting.
Where and when the baby was born were not reported.
Osbourne and Stelly, 26, confirmed their engagement last year.
LGBT community has 'bullied the American people': Bachmann
Beautician charged with giving client fatal silicone butt injection