In the video, Blakely spun a globe, before revealing that she had bought each of her employees two first-class plane tickets to anywhere in the world.
She added: “If you go on a trip you might want to go out to a really nice dinner, you might want to go out to a really nice hotel, and so with everybody’s two first-class tickets to anywhere in the world, you are each getting $10,000.”
The video includes employees’ jubilant and shocked reactions.
“I really want every employee to celebrate this moment in their own way and create a memory that will last them a lifetime! Cheers to 21 years of magic and many more to come,” she wrote on Instagram.
In her toast, she paid tribute to “the women that came before me, and all of the women in the world who have not had this opportunity.”
Blakely has said that when she founded Spanx in 2000, she did so with $5,000 in savings.
Last week, private equity firm Blackstone said it would take a majority stake in the brand. Financial terms were not disclosed, but the firms noted the eight-figure valuation in a news release.
Shapewear is often worn as a figure-hugging undergarment that smooths, slims or otherwise alters body shape. The global compression and shapewear market is expected to reach $7 billion by 2030, according to Allied Market Research.