The 29-year-old digital star shared a collage featuring Ingrid, who turned 27 on Feb. 2, 2016.
In an accompanying note Hannah, who recently finished filming "Dirty Thirty", described Ingrid as an "incomparable... lover and friend."
She wrote: "Happiest of Birthdays to @IngridNilsen - an incomparable (and unconquerable!) feeler and healer, lover and friend. This world ain't seen nothing yet. 💫💛 p.s. Please enjoy this collage of tiny beautiful things. 🤗🤗🤗."
In a recent interview with Larry King, Hannah opened up about how she met Ingrid.
"Online," Hannah joked. "No, she's also a YouTuber."
When King asked her if marriage was in the cards, she replied coyly: "I hope that someday in my life to someone."
Ingrid also posted a snap on Instagram today -- a style-inspired pose which showed off just her jeans and boots.
"Comfy and cozy today," she captioned the image.
Earlier this month Ingrid was among several YouTube stars who interviewed President Obama after his State Of The Union address.
During the interview with the Commander-in-Chief, Ingrid asked why there was a "luxury tax" on sanitary pads and tampons in many states.
The president was totally caught off guard by the question, saying he had "no idea" why states would tax such a thing, and he confessed that he had never heard of that before.
"Recently I was shocked to learn that pads, tampons and other menstrual products are taxed as luxury goods in 40 states," Ingrid, who often speaks about women's issues, told the most powerful man in the world. "I don't think there is anyone who has a period that thinks it's a luxury."
"I think that's fair to say, Michelle would agree with you on that," Obama replied.
While she and Ingrid have the YouTube space in common, they do different types of videos. Hannah rose to fame with her "My Drunk Kitchen" YouTube series. The comedic clips features Hannah attempting to cook or bake various dishes while drinking alcohol.
She has gone on to star in the independent comedy film "Camp Takota" and recently wrapped "Dirty Thirty" which sees her working with Grace Helbig and Mamrie Hart (no relation) again.
Ingrid posts videos that are more in the lifestyle and beauty realm. In 2014, she was the first YouTube star to represent CoverGirl. In June 2015 she uploaded a YouTube video in which she came out as gay.