Taking to her Instagram page on Tuesday to share the happy news, proud mum Millie uploaded a gorgeous photo from her hospital bed. "Welcome to the world Aurelia Violet Taylor," she said.
WATCH: Millie Mackintosh shows off stunning baby shower banquet
"Our little bundle of joy arrived safe and sound and our hearts are bursting with love. I'm signing off for a bit to spend time with my family in our newborn bubble [heart emoji]."
Her husband Hugo quickly commented: "You are our families' hero! We (Aurelia, Sienna and I) love you so much."
The post prompted a huge response from fans, with one writing: "Huge congratulations to you both." Another remarked: "Huge congratulations to you all x." A third post read: "Congratulations and what a beautiful name. Xx."
Millie and Hugo have welcomed their second daughter
The former Made In Chelsea stars, who married in 2018, are also doting parents to 18-month-old daughter Sienna.
Last month, Millie spoke of her excitement of becoming a mother again as she talked about her pregnancy. She told HELLO!: "I've been so busy with Sienna I haven't had much time to focus on being pregnant.
The couple are also parents to little Sienna
"The first pregnancy it was all I thought and talked about. But I sometimes now forget I’m pregnant – and I never thought I'd ever be someone who said that. Then I'll catch sight of myself in the mirror and I'm like: 'Oh, yeah! There’s a big bump!'"
Discovering they were expecting again was a "huge surprise" to the couple. "My first thought was: 'I already have a baby,'" she added. "But having them so close together will have its advantages and you can't plan these things."
Like this story? Sign up to our newsletter to get other stories like this delivered straight to your inbox.