The sports tribunal found there was "insufficient evidence" to back the International Ski Federation (FIS) sanction. But it backed the FIS decision to rule as invalid Mae's results at the Sochi Winter Olympics last year because of the "defective" results of her qualifying events.
Mae, competing under her family name of Vanessa Vanakorn, came 67th and last in the women's giant slalom at the Olympics.
The 36-year-old music star, who has sold millions of albums, became Thailand's first ever female Olympic skier when she competed in Russia.
But Mae, born in Singapore to Thai and Chinese parents, was handed the ban by FIS in November after the body had established that her qualifying event, held in a blizzard in January in Slovenia, in southeastern Europe, was riddled with irregularities.
But in Friday's ruling, the CAS Panel "accepted the position of the FIS that a number of irregularities had occurred in the organisation and management of the four races in question, but could not find, to its comfortable satisfaction, evidence of any manipulation by Vanessa Vanakorn herself that justified the guilty verdict and the slap of a four-year ban."
The CAS panel added that FIS had been right to annul the competition results meaning that "Vanessa Vanakorn remains ineligible to compete in the Sochi 2014 Olympic Winter Games."