Alicia Keys honours stepson Kassem Jr. on his special day

Alicia Keys proved to be a doting stepmom to Kassem Jr.

Taking over to her Instagram account, the singer posted a 19-photo carousel to celebrate her stepson’s 18th birthday on Sunday, December 22.

In addition to the photo dump, Keys, 43, penned a heartwarming birthday note for Kassem Jr., who goes by KJ, which read as, "My amazing young king @yayachronicles !!"

"You are totally unstoppable!! I’m so excited about every moment this year is going to bring!!" she continued. "This is just the beginning of things you can’t even imagine! Keep working hard and bringing that light and gratitude, everywhere you go!!!!"

"The blessings of tomorrow will be greater than we can ever imagine today!!!" The Girl on Fire singer added before wrapping up, saying, "I love you Kassy!! Always your Umi!!! [heart eyes emoji]."

The series of snapshots included pictures of Keys and KJ smiling and posing together over the past years. Among a few family pictures, one image featured the 18-year-old birthday boy wearing an NYU sweatshirt.

Keys’ husband Swizz Beatz welcomed KJ with ex-wife Mashonda Tifrere. While Keys and Beatz share Egypt Daoud, 14, and nine-year-old Genesis Ali.