Jack and his girlfriend Lauren Shippey welcomed son Reuben on Tuesday, 17 December, around two weeks after his scheduled due date.
He weighed in at 8lbs 12oz.
A thrilled Jack announced the news via Twitter, saying: "Baby's here! Thank The Lord, a boy Reuben. 8 pound 12 Masssssive! Was born yesterday night at 22:40 Lauren and Reuben are doing fine."
On 13 December, the actor had updated fans on Baby Shepherd's decision to put off his arrival for a bit, saying: "Just been to works Christmas doo, sober waiting on baby Sheps, 10 days over due!"
Jack, who plays David Platt in the ITV soap, and Lauren announced their pregnancy in May via Twitter, with Jack saying: "Me and @LaurenShippey are pleased to announce we are expecting a baby, we are both very happy. X."
They are already parents to daughter Nyla.
Among those sending congratulatory messages to Jack and Lauren today was Jack's co-star Paula Lane, who wrote: "Massive congratulations @JackPShepherd88 @LaurenShippey on the birth of baby Reuben! #itsaboy xxxx."
More celebrities who have welcomed babies in 2013 below:
Copyright: Love & Lust London