[2] He achieved fame when he created a special foundation cream for Princess Stéphanie of Belgium who lost her self-confidence due to an acute case of acne.

His reputation was further solidified after he treated actress Frida Gombaszoegi's facial scars after being shot in the face by a man she rejected.

On 3 November 1939, the New York Herald Tribune reported that the Ernő László Institute, specializing in beauty treatments and cosmetics, had leased a floor in a building on 677 Fifth Avenue, Manhattan.

Among his clients were the Duchess of Windsor, Doris Duke, Marjorie Merriweather Post, Greta Garbo, Lillian Gish, Grace Kelly, Ava Gardner, Cecil Beaton, Katharine Hepburn, Paulette Goddard, Audrey Hepburn, Marilyn Monroe, and Jacqueline Kennedy Onassis.

The company was purchased in 2002 by Cradle Holdings Inc., a division of corporate finance group Fox Paine.