The CEO and founder of popular shapewear brand Spanx is celebrating the company's new US$1.2bn valuation – by giving all her employees cash bonuses and gifts.

Sara Blakely rewarded each of her workers with $10,000 and two first-class plane tickets to mark more than two decades of growth. 

The CEO thanked her staff during a party last week, and also on social media, as they celebrated investment firm Blackstone's purchase of a majority stake in the clothing company.

At the party, Blakely said: "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, you are each getting $10,000!"

Blakely is known for having started her shapewear business Spanx with only $5,000. Now, her brand is recognised globally. 

"To stand here today, and think about what we've been able to create and what we've been able to do by being authentic and kind and delivering amazing products to women to use their very feminine principles in a very masculine space which is business, leading with intuition, vulnerability ... this marks a moment for female entrepreneurs," Blakely said.

During her speech, she honoured other women in business. "I want to toast the women that came before me and all of the women in the world who have not had this opportunity," Blakely said.