Dan, 23, and EastEnders actress Jacqueline, 21, said in a joint statement that they were "thrilled by our news".
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Jacqueline Jossa and Dan Osborne are expecting their first baby together
The Only Way Is Essex star Dan - who welcomed son Teddy in December with ex-girlfriend Megan Tomlin - added, "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."
A spokesperson for EastEnders also offered their congratulations to the mum-to-be. "Everyone at EastEnders is thrilled for Jacqueline," the rep said.
Jacqueline and Dan have been dating on-and-off for the past year; the actress confirmed their romance was back on in June when she shared a picture of the pair cuddling up on her Instagram page.
Dan Osborne, 23, and Jacqueline Jossa, 21, confirmed their romance was back on in June
Dan went on to praise his girlfriend, who plays Lauren Branning in the BBC soap, in an interview with Star magazine.
"There's not one bad thing I could say about her," he said. "We enjoy each other's company. She's a really lovely girl."
Before news of their pregnancy broke, Dan spoke about how much being a dad to Teddy has changed his life.
"Having Teddy changed my perspective, he makes me want to do better, and be better," the reality star told Heat magazine earlier this week.
"I want him to be proud of me… I'll make sure he has everything he ever needs. Having a baby really changes the way you think about things."