The Pearl Harbour actor and his British actress girlfriend Tamsin Egerton are expecting their first child together.
A rep for Josh confirmed the happy news to Page Six, saying the couple are "beyond thrilled" to be starting a family together.
Josh and Tamsin have always kept their romance away from the spotlight but it's believed they've been dating for around four years.
US star Josh, 36, became a major Hollywood heartthrob thanks to movies like The Faculty, Halloween H20, Pearl Harbour and 40 Days and 40 Nights.
He can currently be seen in the horror series Penny Dreadful.
Meanwhile, actress Tamsin, 26, rose to fame as schoolgirl Chelsea Parker in St Trinians and its sequel St Trinians II: The Legend of Fritton's Gold.
Josh and Tamsin met on the set of romance movie The Lovers, playing a married couple.
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