Courtesy of Ashlee Simpson/Instagram

Ashlee Simpson’s son Bronx is growing up — and up, and up.

The singer celebrated her eldest son’s 16th birthday via an Instagram carousel on Wednesday, November 20. Her post included a pic of Bronx towering over her as Simpson, 40, leaned on his shoulder. Bob Marley’s “Redemption Song” played in the background.

“Being your mom has been the greatest joy of my life,” she wrote in the caption. “You are my rock my soul. My ride or die. You have been the greatest blessing in life that I could have ever dreamed of. I would not be me without you.”

Simpson shares Bronx with ex-husband Pete Wentz. She was married to the Fallout Boy bᴀssist from 2008 to 2011. She also shares daughter Jagger, 9, and son Ziggy, 4, with husband Evan Ross.

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“Thank you for choosing me to be a mom, and YOUR mom,” Simpson continued. “You are so calm, consistent, brilliant, loving, kind hearted, thoughtful, funny, mysterious, and incredibly awesome. I thank God every day that I get to be your mom. You are a true gift to this universe and I’m so lucky you are my very grown, and cool baby… happy 16th birthday. I love you.”

In the past, Simpson has gushed about raising Bronx with Wentz, telling Olivia Allen and Rachel Bilson on their “Broad Ideas” podcast that she won the “coparenting lottery.”

“I feel like we also started [coparenting] when Bronx was two and a half so he didn’t know different,” she explained in February. “We used to have that three, four thing, you know the days that you have your kids? And I think maybe he was like 10, he was like, ‘No I want to do one week, one week.’ We kind of flow with that and it’s been like that for so long and that’s what works and we’re so easy with each other, we’re like, ‘You want to go on tour?’ It’s been a real flow and natural good thing.”

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Ashlee Simpson and Evan Ross wear a lot of hats as musicians, reality stars and actors — but they are doting parents too. The “Pieces of Me” singer welcomed her first child, son Bronx, with her ex-husband, Pete Wentz, in 2008. Following their 2011 split, Simpson moved on with Ross and welcomed their daughter, Jagger, […]

Simpson’s post also included sH๏τs of her pregnancy with Bronx — baby belly fully featured — and Bronx as a baby, dressed up for Halloween, wearing sunglᴀsses in his car seat, petting a pair of horses and more.

Courtesy of Pete Wentz/Instagram

Now 16, Bronx has been learning to drive, Simpson told Us in August.

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“It’s so exciting, and he’s such a great, cool, like, old soul so I feel like he’s ready for 16, and he got his permit,” she said.

Simpson concluded her post with a little TMI for her son.

“Also you were born to this song,” she concluded. “Thank you for making me the luckiest.”