The 32-year-old model announced in an Instagram post Sunday that she's expecting another child with husband, Kings of Leon frontman Caleb Followill.
Aldridge showed off her baby bump in a photo at the beach. The picture shows the expectant mom wearing a printed bikini and smiling for the camera.
"SURPRISE," she captioned the post.
Aldridge is already parent to 6-year-old daughter Dixie Pearl with Followill. She shared a family photo earlier in the day from the Wilson County Fair in Lebanon, Tenn.
"Family FunDay," the star wrote.
Aldridge discussed motherhood in an interview with Porter magazine published in March.
"My daughter is my best friend and the only person that I want to hang out with," the model said. "We like to go to the park, where there's an amazing science center. She loves science."
"I am so proud to be a mom; it's the greatest achievement in my life without a doubt," she added.
Aldridge was made a Victoria's Secret Angel in 2010. She is also known for her work with Sports Ilustrated, Coach and rag & bone.