Kim, 34, posted a stunning picture of her sibling on micro-blogging site Twitter, reported Daily Mirror.
"To the sweetest girl in the world Happy Birthday I love you so much," she wrote.
Khloe also posted a clip of a very excited 'Kendall'. The clip shows her mouth moving but nothing else as she squeaks about being giddy with excitement.
"Oh I think @kendalljenner is excited
#HappyBirthdayKendall," Khloe posted.