Jamie Lynn Spears is an engaged woman! Britney’s little sister is marrying her boyfriend of three years, Jamie Watson, 30.

RELATED: Britney Spears calls off her engagement!

Spears, 21, announced her news on Twitter, and posted a picture of she and her fiance, as well as a gorgeous closeup of her ring. “Guesssss what??????” she wrote next to the picture.

Minutes later, she posted another photo: a close-up of the huge, round-cut diamond. “He did good,” she wrote, with a smiley-faced emoticon.

This will be the first marriage for the former Nickelodeon star. She was previously engaged to Casey Aldridge, the father of her 4-year-old daughter, Maddie. They split for good in 2010.

Spears’ engagement comes just two months after news of her older sister’s broken engagement. Britney, 31 — married twice before, to pal Jason Alexander and ex Kevin Federline, with whom she has two kids — was set to wed boyfriend Jason Trawick until the couple’s January 2013 split.

That is one of the more beautiful engagement rings I’ve seen in a while! It’s simple, yet beautiful!

PHOTOS: Jamie Lynn Spears poses poolside with her three-year-old daughter Maddie!

Makes me nervous that she’s getting married so young…. but hopefully it works out. I was married at 22 – and while I’m still married now, I will say getting married that young is harder! Pretty hard to not be selfish when you’re 21 years old.

Britney Spears, her older sister, is thrilled. “So excited and happy for my sister,” Britney, 31, tweeted early this morning. “Congrats @jamielynnspears – love you.” Jamie Lynn shared her dazzling engagement ring with her Instagram followers and praised her hubby-to-be’s selection: “He did good.”

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