Mandy Moore is now mom to her own Big Three.

The This Is Us star and her husband Taylor Goldsmith—who tied the knot in 2018—welcomed their third child together, a baby girl.

"Lou is here!" she captioned a Sept. 25 Instagram photo of holding her newborn while gazing up at her husband, "Louise Everett Goldsmith arrived happy, healthy, expeditiously and right in time for Virgo season. She is our absolute dream girl and her big brothers are already as obsessed with her as we are." 

She continued, "Endlessly grateful for our family of 5 (and our very own big three) and soaking in every moment of this special time."

Mandy announced her pregnancy in a May 31 Instagram post that featured their two sons—August “Gus” Harrison, 3, and Oscar “Ozzie” Bennett, 21 months—wearing shirts that said, “Big" and “Middle,” respectively.

"Sometimes life imitates art," the 40-year-old wrote in the caption, referring to her character on the NBC drama who has two sons and a daughter. "The third in our own Big Three coming soon. Can't wait for these boys to have a baby sister.”

Mandy had previously expressed being open to add a third little one into their family.

"Truth be told, I haven't shut the door on a larger family," she told E! News in March 2023. "I don't know what my husband is thinking. I know right now, he's sort of like, 'Whaaat? That's crazy! It's so hard.' And it is. It's so hard. It's non-stop, all hands on deck right now. So maybe, perhaps. but I don't know."

After all, her oldest son has proudly stepped into the role of big brother and he and Ozzie are more than just siblings—they’re best friends.

"Gus is like a superb big brother," the Walk to Remember actress continued. "He relishes that role. He's not super jealous. Once Ozzie got here, he was just super protective of him. He understands how fragile Ozzie is. He wants to cuddle him. It's very sweet."

But for Mandy, pregnancy hasn’t been all sunshine and rainbows as she’s shared insight into her experience with melasma.

But through it all, the “Candy” singer has championed the resilience that comes with motherhood.

"I honestly don't know if you can do it all but as a mom, as a working mom, I'm trying my level best," she explained to E!. "And I try to just sort of have grace for myself and recognize that each day is going to throw a different obstacle my way and just to sort of find my way through it. Keep putting one foot in front of the other."

And Mandy has come a long way in her journey to being a mother of three, considering three years ago she left the fertility doctor believing that an endometriosis diagnosis meant having children of her own would be impossible without surgery.

“I was fully prepared to go have surgery and fix my uterus and hopefully get rid of the endometriosis, if it was there,” she told Romper in January 2021. “It was nice to have a plan and to know ‘Okay, well this is why I haven’t been pregnant yet.’”

Luckily, she found out that she was expecting her first child just before going in for surgery. And she knew even before becoming a first-time mother that Taylor, 38, was going to be an amazing dad.

“I think he’s been suited to be a father pretty much his whole life,” she continued. “He’s been gearing up for this. Like in the morning, it’s funny, I’ll reach for my phone and he’ll reach right for whatever baby book he’s reading.”

Keep reading to reminisce on their sweet family memories in photos.  

Mandy Moore and Taylor Goldsmith welcomed son August "Gus" Harrison in February 2021 and Oscar "Ozzie" Bennett Goldsmith in October 2022.

"I can't believe we get to do this parenthood journey together," Mandy wrote to her husband for Father's Day 2023. "The 3 of us are the luckiest to have you, T. Love you to the moon and Happy Father's Day!!!"

Mandy shared in a tribute to Taylor on Instagram, "You were writing songs about coaching Little League well before we got married so I had *some* inkling that being a Dad was something you would excel at but I truly had no idea just how exceptional and natural you'd be until we were in it." 

"I marvel at all you bring to the table- your patience, your gentle nature, your willingness to change a diaper or get up with a crying baby without me ever asking or to run around and get in the dirt with a very active toddler at any moment," the actress continued in her message. "Your ability to get Gus to eat something he'd flat out refused with me or elicit Ozzie's immediate laughter, your music curation for our boys- which is TOP NOTCH… I could go on and on."

"We had an early Birthday bash with friends and family for Goosey," Mandy wrote on Instagram in February 2023. "2 years with the sweetest, goofiest guy has absolutely flown by. We're the luckiest folks around to be in your orbit, Gus Goldsmith."

"I have been quarantined with this guy for over 6 weeks and we still really like each other," Mandy shared on Instagram in April 2020. 

"Me and my love," Mandy shared on Instagram when teasing another duet performance. 

Whether performing music together or cuddling on the couch, these two make one cute couple. 

The Dawes musician and the actress/singer collaborated on a song for This Is Us.

"@mandymooremm @siddkhoslamusic and I the day we recorded "Invisible Ink" from last night's episode of @nbcthisisus," Goldsmith wrote on Instagram in November 2018. So honored that Sidd asked me to help him write it and then to get to record it with my favorite human. Please go check it out on Spotify or Apple Music."

The two hike in Kilimanjaro National Park in August 2018.

The cute couple step out for the annual Communities in Schools Celebration in Los Angeles in May 2018.

"The look of two tired people who were awoken by the hotel fire alarm at midnight," Moore wrote on Instagram in September 2018. "Also the look of two people grateful for 24 hours together after being apart almost a month. It's always a worth a trip to see @dawestheband play a gig too.... you're in for a treat tonight, #portland."

The two attend the 2017 Emmy Awards.

"#FBF to Emmy Sunday when this guy flew across the country the morning of just to share the day with me," Moore wrote on Instagram.

Mandy shared this photo in honor of the couple's two-year anniversary in July 2017 with the caption: "The best 2 years. Never not smiling with you, T."

"So proud of this guy and the whole band for an absolutely electric hometown show last night," Moore wrote on Instagram in January 2016.

The This Is Us star is not afraid to rock a pair of heels and be a bit taller than her man. #couplegoals

The couple enjoyed a mini-vacay in San Francisco to see an iconic landmark.

As Ed Sheeran would say, "You can keep me inside the pocket of your ripped jeans." Or, according to Taylor, as a bookmark in your favorite book.