Kate Hudson officially has a teenager on her hands.

The star's son, Ryder Robinson — who she shares with her ex-husband, singer Chris Robinson — turned 13, and the proud mom is gushing over her growing son on his birthday.

"Thirteen years… Today I reflect on how lucky I am to have spent my entire adult years being Ryder's mother," she shared on Instagram. "My dear Ryd man! Today you are 13! Hard to believe but I'm staring right at you and my goodness yes you are a teenager!"

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Thirteen years… Today I reflect on how lucky I am to have spent my entire adult years being Ryder's mother ❤️ My dear Ryd man! Today you are 13! Hard to believe but I'm staring right at you and my goodness yes you are a teenager! I couldn't be more in love with who you are as a person and who you are growing into as a young man. Smart, funny, joyful, tolerant, perceptive, empathetic, loving, you continue to maintain the beautiful attributes of your true nature and I will always be there as your touchstone to help nurture them or rediscover them if they ever get cloudy. But watching you independently keep these characteristics close and alive has been a wondrous journey in which I look forward to witnessing every waking hour. Happy Birthday baby!!! 🎂 13 is looking pretty awesome so far!!! I love you ❤️ #RyderIsThirteen #HappyBirthday #ProudMama

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"I couldn't be more in love with who you are as a person and who you are growing into as a young man," she added. "Smart, funny, joyful, tolerant, perceptive, empathetic, loving, you continue to maintain the beautiful attributes of your true nature and I will always be there as your touchstone to help nurture them or rediscover them if they ever get cloudy. But watching you independently keep these characteristics close and alive has been a wondrous journey in which I look forward to witnessing every waking hour."

kate hudson ryder getty images

Kate is also mom to five-year-old son Bingham Bellamy, who she shares with ex Matt Bellamy.

Now, with this latest milestone, the star is one proud mama.