The former centerfold thanked the Playboy magazine founder with an emotional Instagram message.
“Happy birthday Hef!!” she wrote. “Thank you for EVERYTHING. People might not understand you but that’s because they’ve never had the chance to know you like I do. I’ll celebrate you forever!!!”
Wilkinson became a household name when she was just 18-years-old and moved into the Playboy mansion to star in The Girls Next Door.
She appeared on the reality series alongside Hefner’s other girlfriends, Holly Madison and Bridget Marquardt.
Wilkinson left the mansion and moved in with her now husband Hank Baskett in 2009, but went on to land two other reality shows, Kendra followed by Kendra on Top.
The 31-year-old maintains a good relationship with Hefner and has described him as “family” and an “angel.”
To celebrate Hefner’s milestone, Us Weekly rounded up some of his best — and most ridiculous — life lessons.
Watch the video above to see some of his infamous quotes from the 1970s to today!