The 27-year-old was stripped of her fourth-placed finish in the 48 kg category held on Saturday.
Nan Aye Khine gave a urine sample on Thursday which tested positive for the unnamed steroid, the IOC said.
The commission unanimously ruled
It also requested the International Weightlifting Federation to modify the result of the event and consider any further action.
Under the World Anti-Doping Agency code, a positive drugs test is accompanied by an automatic two-year ban.
Myanmar's national Olympic committee was ordered to return the diploma awarded to the athlete for finishing fourth to the IOC.
She is the second athlete to test positive during pre-Games testing in Athens following Kenyan bantamweight boxer David Munyasia, who was expelled on Friday after a positive doping result for the banned substance cathine.