A major fundraising drive is now underway to fund the renovation.
A new education space, larger café, new toilets which will be accessible directly from the main level of the Cathedral Nave and a passenger-operated lift to access the lower level gallery and link to the café and Cathedral Nave have been awarded planning permission by the Cathedrals' Fabric Commission for England and Coventry City Council.
The Cathedral Dean, Rev John Witcombe, said in a statement: "I am delighted that we are preparing to make our unique building fully welcoming and accessible to increased numbers of visitors in preparation for the celebrations of 2021 and beyond.
"The works are transformational and necessary to position the Cathedral as a major social, cultural and community hub for the city as well as creating a modern, flexible and accessible space offering a warm welcome to all."
The aim is for the extension to be completed before Coventry becomes the UK City of Culture in 2021.
Minister for Local Growth Jake Berry MP said: "We're committed to boosting economic growth across the Midlands Engine and rebalancing the economy so that it works for everyone.
"That is why I am really pleased to see £772,000 from the Government's Local Growth Fund helping to make these exciting plans for the Cathedral a reality.
"With new facilities and improved access, the plans will improve the visitor experience for the local community and tourists alike, which is particularly important as Coventry prepares to celebrate being UK City of Culture in 2021."
A total of £3.5 million is needed to carry out all the plans. The government's provision of £772,000 and £1.45 million from other funders has helped make the Cathedral's aim for feasible.
Helen Peters, board director at the Coventry and Warwickshire Local Enterprise Partnership (CWLEP) leading on culture and tourism, said: "This is a historic development at a building which is renowned throughout the world and the allocation from the Local Growth Fund will play a part in creating a new chapter in its future.
"This is an important time for Coventry with 2021 on the horizon when we are bestowed with the honour of being UK City of Culture and the development plans will give even more audiences the chance to enjoy this wonderful building."
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