The official Xinhua News Agency reported representatives from investors in China, Myanmar, South Korea and India were on hand for the inauguration of the 430-mile pipeline.
Myanmar Vice President U Nyan Tun joined his country's energy minister in flipping the switch to start the pipeline Sunday afternoon local time.
The pipeline passes through Myanmar's volatile Rakhine state, the site of deadly communal clashes.
Pipeline investors donated $50,000 in aid and 10 tons of rice to communities affected by the violence, the news agency reported.
The pipeline is designed to carry 400 billion cubic feet of natural gas per year.
Myanmar will receive 20 percent of the gas, which Xinhua reported will provide a source of economic stimulus for Myanmar.