It follows years of sustained protests by local residents
The Government has given consent for Shell to begin begin operating the Corrib Gas pipeline.
A statement issued this evening from Minister for Communications Alex White said the consent is subject to 20 conditions relating to environmental management, operation, control and monitoring.
The Department of Communications, Energy and Natural Resources says the project will provide 42% of the all-island gas demand over its first two years of operation.
Minister White said the Government's planned transition to a low carbon economy "will take time, and fossil fuels will remain part of our energy mix for some years to come."
"In this context, the development of indigenous gas resources will deliver significant and sustained benefits, particularly in terms of enhanced security of supply, import substitution, national and local economic development, and fiscal return," he added.
Shell E&P Ireland, which operates the pipeline and the onshore terminal, was granted an industrial emissions license by the Environmental Protection Agency earlier this year, meaning it required only ministerial approval before beginning operations.
The offshore gas field was first discovered in 1996 and development of the project began in 2004. However, local residents protested the development on safety and environmental grounds, with the 'Rossport Five' jailed for 94 days after violating a court injunction to to interfere with the pipeline's construction.
A final route for the pipeline was approved in 2011 and construction was completed last year.
The saga also received international attention and was the subject of 'The Pipe,' a 2010 documentary.