Harper Beckham is growing up right before our eyes!

David and Victoria Beckham's celebrated the fifth birthday of their only daughter on Sunday, less than one week after their 17th wedding anniversary. The pair shared sweet messages and even sweeter photos of their baby girl to mark her big day.

WATCH: Victoria and David Beckham Celebrate 17 Years of Marriage with Flashback Wedding Photos

Victoria, 42, shared an absolutely precious shot of her and Harper giving each other a smooch while wearing sunglasses in an infinity pool.

"Happy Birthday baby girl ??? We all love you so much ??? X @davidbeckham @brooklynbeckham kisses from mummy X"” the fashion designer captioned the Instagram pic.

David penned a lengthier note to his and Victoria's youngest child alongside a gorgeous black-and-white shot of Harper planting a kiss on her dad's cheek.

"Happy birthday to my Pretty Lady ?," he wrote. "In 5 years baby Harper has brought so much love into our family ... Such a special girl in so many different ways we are so lucky to spend each day with such a beautiful soul ... We adore you baby girl happy birthday love Daddy ❤️ @victoriabeckham."

EXCLUSIVE: David Beckham Opens Up About His Children Becoming Stars

The 41-year-old former soccer pro is known for getting sentimental, especially when it comes to the two ladies in his life. David gushed over his wife on her 42nd birthday in April, and last year, he admitted to being stricter with Harper than with his three sons, 17-year-old Brooklyn, 13-year-old Romeo, and 11-year-old Cruz.

"I have no power with that little girl -- no power whatsoever," he told ET in September while promoting his H&M Modern Essentials campaign in New York City. "I love all my children, of course, equally but I'm definitely stricter with the boys than I am Harper, which gets me in trouble with my wife of course."

Relive David's birthday message to Harper on her fourth birthday last year in the video below.

Related Gallery

Stars Share Pics of Their Cute Kids