Wearing a skintight, leather mini-dress, the "Level Up" singer took to TikTok to show love for her NFL player boo ... dancing around to a birthday song while blowing him a kiss.

She later hit Instagram to tell the Denver Broncos quarterback just how much she loved him on his big day Tuesday.

"Intelligent, Beautiful, Loving, Caring, Thoughtful, Consistent, Special, Anointed, Rare, A Legend, a Winner, Everything that is YOU!" she wrote in the caption of steamy photos of the couple. "I love you so much Birthday Boy @DangeRussWilson! Today a King was born! I love you so much! I’m so proud to celebrate you today and everyday 👑"

Russ, like always, cherished both posts from his wife of 6 years ... responding in the comments, "Uh oh ... Momma TikTokin' again."

"I am grateful I get to spend the rest of my life with you," he added. "And one day Eternity in Heaven. I love you Mrs. Ciara Wilson."

As for how they celebrated ... they spent at least part of the day giving back to the community, with the two dropping by Centura Parker Adventist Hospital in Colorado to visit some patients.

Of course, there was a birthday cake involved, too.