The Game of Thrones star has given birth to a baby girl, named Willa.
The British actress reportedly gave birth last Wednesday at a Los Angeles hospital already.
A source close to the couple said: “The couple is keeping things very hush-hush, but their friends and family are super excited for them.”
An insider also told Entertainment Tonight: “The couple is already obsessed and can’t stop gloating about their new addition.
“The couple is taking time to enjoy this special moment and have only shared the news and updates with family and friends.
“With the [Coronavirus] pandemic, Joe and Sophie have been very cautious about who is around them and their little girl.”
Sophie and Joe got married last year in a casual affair in Las Vegas and a more lavish event in France.
The 24-year-old actress revealed recently that she “can’t wait” to become a first-time mother.
A source said last month: “Joe and Sophie are excited to be new parents and have been enjoying the process of getting ready for their baby.
“Sophie and Joe have been trying to also stay active going on walks and hiking. The whole Jonas family is looking forward to showering the new addition with love.
Sophie previously admitted she is “loving” being in quarantine at home with Joe amid the Coronavirus pandemic - but he feels like he’s in “prison”.
Speaking about their time in lockdown, she said: “I’m kind of loving it. I’m an introvert, I’m a homebody, if I could stay at home all day I would, so this is great for me.
“Joe and I. .. everything seems to be working out in my favour here because Joe is a real social butterfly and I struggle to lock him down and just spend time with me. It’s like a prison for him, but it’s great for me.”