The deal also gives India's biggest refiner a 10 percent interest in the Malaysian company's proposed Pacific NorthWest liquefied natural gas facility on Canada's West Coast.
IOC did not disclose financial details of the deal, but the Indian cabinet approved the purchase of the stake for C$1 billion in February, a government source told Reuters at the time.
Petronas bought Canada's Progress Energy Resources Corp in 2012 in a C$5.2 billion ($4.74 billion) deal that included the shale gas properties.
Indian companies, like their Asian peers, have been scouting for oil and gas assets abroad to meet rising domestic demand.
India's gas demand will rise to 466 million cubic metres per day (mcmd) in 2016/17 ending March 31 from 286 mcmd in 2012/2013, according to government estimates, while its supply will be only half that amount.
IOC said it would lift 1.2 million tonnes of the super-cooled gas a year from the facility for a minimum period of 20 years to partly meet the requirement of its planned 5 million tonne a year Ennore LNG terminal in Southern India.
The LNG plant is likely to be ready in 2016/17, with exports starting in late 2018, IOC said. ($1 = 1.0965 Canadian dollars)