The 27-year-old actor and his girlfriend Sheila Hatsadi are "thrilled and excited to be expecting their first child" later this year, his representative confirmed to Usmagazine.com.
According to friends of the couple, 24-year-old burlesque dancer Sheila - who met the actor when he was touring with his band 100 Monkeys - is currently five months pregnant.
Jackson - who is best known for playing Jasper Hale in the `Twilight Saga` movie series - is said to have traded in two of his cars for a more family-friendly Lexus Hybrid SUV in preparation for the new arrival.
The actor recently admitted he would love to reprise his role of Jasper for even more `Twilight Saga` films in the future.
He said: "They are always discussing it, it depends how they would go about it. I have loved my character and I have loved playing Jasper through the years, so if there is an extension of playing Jasper - more so in his own element, maybe go back in time and do a vampire western, show Jasper where he came from - I would be down for that. I would sign up for that."