Curtis' reaction comes just hours after Lohan's rep confirmed the news that she and her husband welcomed a baby boy.
It's a magic Monday indeed!
Curtis took to Instagram shortly after news broke that Lohan welcomed her first child with husband Bader Shamas and shared a photo of her and her Freaky Friday co-star.
"MAGIC MONDAY! My movie daughter just made me a movie grandmother," Curtis wrote. "Blessings to Lindsay and Bader for the birth of Luai! @lindsaylohan."
Fans of the film will remember that the women previously played mother and daughter in the 2003 remake of Freaky Friday.
Curtis previously shared her adulation over Lohan becoming a mom back in April, with The Haunted Mansion actress re-posting a series of images from Lohan's baby shower, offering praise and well-wishes for her former co-star.
"My friend and film daughter @lindsaylohan is growing up! So thrilled for her. What a mama she will be," Curtis wrote.
Curtis' post comes just hours after the actress' rep confirmed the news that she and Shammas welcomed a "beautiful, healthy" son named Luai Monday.
"The family is over the moon in love," Lohan's spokesperson said.
Her real-life mom, Dina Lohan, also shared her excitement with ET, adding, "We are so blessed and filled with love and joy. He came two days early and I’m getting on a plane tonight and going straight to the hospital."
Lohan and Shammas, a Dubai-based financier, first announced they were expecting in March 2023. Lohan shared the news with her fans on Instagram, posting a "coming soon" photo with the caption, "We are blessed and excited! 🙏🤍👶🍼."
Dina also celebrated after Lohan first announced her pregnancy, telling ET, "I am over the moon, filled with so much joy and happiness for my daughter and her husband, and my family is thrilled. It's a beautiful time for us all."
She also shared an adorable throwback photo of herself playing with her famous daughter as an infant, and added, "My baby is having a baby!"
Lohan's father, Michael, posted his own celebration on Instagram, writing, "THE CAT'S OUT OF THE BAG! HER BEST ROLE YET! MOMMY!!! God bless her and Bader."
Lohan and Shammas revealed in 2021 that they were engaged. The couple married in April 2022, and later announced their nuptials to the public that same July.
For more on the arrival of Lohan's little one, check out the video below.