"Happy birthday to the most beautiful, inspirational person in my life," he wrote in the caption.
"Love you so much! Happy birthday mum."
Victoria Beckham also uploaded a few Instagram photos of her 42nd birthday.
She shared a picture of some birthday cards from her kids, including one with Harper's handwriting.
"Thank you to my beautiful husband and babies for making my day so special, I am so happy #luckymummy," she wrote.