The actress has been dating The Only Way Is Essex cast member Dan Osborne since the end of last year.
Jossa told The Mirror that she is “thrilled” over the pregnancy, while hunky Dan added that he feels “blessed” to be becoming a father again.
“Becoming a father has been the most amazing thing to ever happen to me. I can’t believe I’m going to be a dad again – I’m truly blessed.” – Osborne
Osborne fathered a son, Teddy, with his former girlfriend Megan less than one year ago.
A spokeswoman for EastEnders said: “Everyone at Eastenders is thrilled for Jacqueline,” while a source adds: “It does mean Jacqueline will have to take some time out, which will have to be written into the storylines, but producers are being incredibly supportive.
“She’s expected to give birth early next year.”
Jossa has played Lauren Branning in the soap since 2010, taking over from Madeline Duggan who had portrayed the character for four years.