The `Juno` scriptwriter welcomed her first child with husband Daniel Maurio into the world on Tuesday morning (27.07.10).
The baby weighed in at 7lbs 2oz and both mother and baby are said to be doing well.
Diablo - who was born Brook Busey - and Daniel have named their son Marcello Daniel Maurio.
She announced the happy news via her twitter page, writing: "We had our boy early this morning! Marcello Daniel Maurio, 7lbs, 2oz, lightly mustachioed. (sic)"
Let`s hope Diablo doesn`t pass on some of the same fears about growing up onto her son as she had.
The 32-year-old writer previously revealed the story behind her movie `Jennifer`s Body` - which stars Megan Fox as a dead cheerleader who returns to kill and eat her classmates - was inspired by her own teenage angst.
Diablo said: "When I started the script, I was thinking about what`s scary to me and I decided girls are scary! One of the first lines of the movie is, `Hell is teenagers`.
"If you think about all the subgenres of horror - vampires, werewolves, zombies - none of these transformations are as profound as puberty. The experience of becoming an adolescent is horrifying."