Rob Kardashian has thanked Blac Chyna's son for helping him fall in love with her.

Rob Kardashian

Rob Kardashian

The 29-year-old sock designer took to Instagram to wish four-year-old King Cairo a happy birthday on Sunday (16.10.16) and admitted one of the first things that attracted him to his fiancee - who is due to give birth to their daughter next month - was seeing how good a parent she is.

Alongside a cute picture of himself and King on a slide, he wrote: "HAPPY BIRTHDAY KING‼️ THANK YOU for letting me see what a great Mama you got ! That was the first thing I fell in love with,,, The way she Loves FOR You is something I can't wait for ! (sic)"

And Rob also spoke of his excitement at his impending fatherhood.

He posted: "Can't wait for the bond I'm going to have with my daughter so Thank You King for allowing me to see that! Everybody Loves You! HAPPY BIRTHDAY WOOHOOOOOO TURN UP ! GO DODGERS (sic)"

The young birthday boy celebrated at the weekend with two Ferrari-themed birthday parties.

His mother, joined by Rob's mom Kris Jenner, threw a Lego Ferrari bash, while the following day, King's dad Tyga and girlfriend Kylie Jenner - Rob's half-sister - threw another party at the 19-year-old beauty's Los Angeles home.

Little King was surrounded by sports car decorations, including a racing car made entirely out of balloons that rested on top of the swimming pool, a racetrack, a Ferris wheel, a trampoline, an inflatable slide, and horses at his party.

Kylie's family, including Kendall Jenner, Kourtney Kardashian, Scott Disick and their three children Penelope, four, Mason, six, and 22-month-old son Reign, joined the couple and King to celebrate the special day.

Kim Kardashian West also attended the event with her three-year-old daughter North, as well as 60-year-old momager Kris and Caitlyn Jenner.

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