The 45-year-old Scream star and his wife of over a year took to their social media accounts to share the exciting news, giving their two-year-old son Charlie a starring role in the adorable announcement.
David - who also has 12-year-old daughter Coco with ex-wife Courteney Cox - uploaded a sweet video of Charlie holding a picture of the baby scan.
He captioned the clip: 'So incredibly blessed and honored that my wife @christinaarquette is pregnant with a baby boy!
'Thank you Christina and humbled gratitude to G-D for this tremendous gift! Charlie and Coco are so excited and I am over the moon!!!'
Christina later shared her husband's Instagram post to her own account, and the messages of congratulations from fans have been flooding in for the pair since.
One user wrote: '@davidarquette congrats again, Big Daddy! Enjoy it all and be strong for them. You're a great Father', and another added: '😍😍😍 sooo exciting... Charlie will be the best big brother!'
David and Christina began dating in 2011, but had an on-off relationship until Christina fell pregnant with Charlie in 2013. The couple got engaged three months after welcoming their son, and were married less than a year later on 12 April 2015 in Los Angeles.
Courteney Cox with the couple's 12-year-old daughter, Coco Riley Arquette
The news comes shortly after David tragically lost his sister Alexis Arquette, who'd been battling HIV for 29 years, just last month. He took to Twitter on 16th September to share a message about his sister, posting a photo of Alexis next to lyrics from the Rolling Stone's song, She's a Rainbow.
'She's like a rainbow,' he wrote in his tweet, followed by lyrics that read: 'She comes in colors. Everywhere she combs her hair. She's like a rainbow.'
Thank you all for your love and kind words about Alexis. My hero for eternity pic.twitter.com/Z18xLtYTBv— David Arquette (@DavidArquette) September 11, 2016
On the day of his sister's death, David also shared a photo of her with the caption: 'Thank you all for your love and kind words about Alexis. My hero for eternity.'