The advert stirred up a storm of debate online, with many Twitter users critical of the advert itself as well as the decision to withdraw it.
One person wrote on a Thai-language forum Pantip.com: "I'm perfectly fine being dark-skinned and now you're saying I've lost? Hello? What?"
"Suggesting people with dark skin are losers is definitely racist," wrote another.
Seoul Secret quickly withdrew the advert, although it could still be seen on YouTube on Friday, and offered a swift apology.
"What we intended to convey was that self-improvement in terms of personality, appearance, skills, and professionalism is crucial," the firm said.