Fergie has marked her 50th birthday by writing a letter to her "younger self".

The singer - who is best known for starring in the Black Eyed Peas - has taken to Instagram to share the letter with her followers.

Fergie - who turned 50 on Thursday (03.27.25) - wrote on the photo-sharing platform: "I honestly didn't know what to post to mark this landmark number, so I started with a letter to my younger self.

"Dear little Stacy, one day you'll be 50 and you'll be proud of yourself. You won't have it all figured out, but you realize …. who does? Success really is in the journey, and true happiness can be found in the smallest simple moments. Keep loving deeply with all your heart, and keep working on yourself. It always all makes sense later. I love you. (sic)"

Fergie's post features a throwback photo of herself, a screenshot of Billboard's list of the top women artists of the 21st century, and a photo of her 11-year-old son.

Fergie - who has Axl Jack with ex-husband Josh Duhamel - continued: "I added the Billboard chart because I wanted to say THANK YOU. (thank u really tho;) It was a beautiful surprise and really made me feel like my music means something.

"I also could not acknowledge this milestone without including my son Axl Jack, the sweetest love I've ever known. You make me want to be a better human every day.

"Onward and upward [cake emojis] (sic)"

Fergie was married to Josh Duhamel between 2009 and 2019, and the actor previously admitted that they simply "outgrew each other".

The 52-year-old star also revealed that he's "made peace with that part of [his] life", adding that he still has a "great relationship" with the singer.

Speaking on 'In Depth With Graham Bensinger', Josh shared: "I think we kind of outgrew each other and had very different interests.

"I made peace with that part of my life. She and I have a great relationship. Both raising that boy together. There wasn't anything wrong with it. We had a great time."