Jessica Simpson has finally confirmed she's pregnant again!

As Us Weeklyexclusively revealed on Nov. 28, Simpson and fiance Eric Johnson are expecting their second child together.

PHOTOS: Jessica's maternity style

On Tuesday, Dec. 25, the Fashion Star mentor tweeted a photo of daughter Maxwell, almost 8 months, sitting on a beach with "Big Sis" written in the sand.

"Merry Christmas from my family to yours!" Simpson, 32, wrote as the caption. In the adorable snapshot, Maxwell is dressed in a red-and-white striped onesie, a red bow in her hair and has a big smile on her face.

PHOTOS: Jessica's body evolution

Jessica Simpson and Eric Johnson
Credit: James Devaney/WireImage

Simpson's second pregnancy "definitely wasn't planned," a pal told Us. But she "loves being a mom and "is overjoyed."

Wearing a form-fitting black dress, Simpson tried to hide her growing baby bump at BFF Cacee Cobb's wedding Dec. 15.

PHOTOS: Maxwell Drew's baby album

"I was the maid of honor last night for my BF Cacee Cobb," she tweeted. "She was the most beautiful bride I have ever seen in my life!" The pregnant star included a photo of herself and Johnson at the wedding, with her bouquet covering her belly. 

After welcoming her first child in May, Simpson became a spokeswoman for Weight Watchers and lost over 50 pounds. "Congrats to Jessica Simpson, Eric and big-sister-to-be Maxwell!" Weight Watchers tweeted Tuesday. "Your WW family is so thrilled for you. What an amazing year you've had!"