The scheme to repair decaying stonework, rotting woodwork and a badly damaged roof at Howden Minster has been welcomed by the Archbishop of York, Dr John Sentamu.
English Heritage will cover more than half of the £522,000 estimated cost, but the minster's finances will be exhausted by funding the balance.
The minster's Parochial Church Council has agreed to carry out work recommended by English Heritage that entails the restoration of the pinnacles and stonework of the west front.
Investigations into other parts of the building will establish priorities for the next phases of restoration.
Dr Sentamu said: "I am delighted that an enthusiastic band of supporters is taking on the mammoth task of restoring this church for the benefit of future generations."
The Minster Church of St Peter and St Paul is an East Yorkshire icon with its tower dominating the local landscape.
It was built as a centre for missionaries and work on the minster began in 1228 before it was completed in 1404 by Bishop Walter de Skirlaw, Prince Bishop of Durham.
Its radical architecture and startling scale reflect the wealth and influence of the Bishops of Durham, who held the Manor of Howden and built a church to rival York Minster.
The church is famous for its ruined choir, the roof of which collapsed in the 18th century after many years of neglect.
This part of the church was simply walled off and is now in the care of English Heritage.
Brian Greenwood, who is one of the minster's church wardens along with Richard Battersby, said: "We see this project as the beginning of an on-going period of regeneration, and are looking at ways of re-ordering the interior so that this great building can become the centre of cultural and social activity for the town it once was.
"The task facing us is a daunting one, but it would be a tragedy if this glorious building were to be allowed to fall."
Preparatory work should begin next month.
n Anyone wishing to support the work can send donations to The Howden Minster Appeal, 8 Orchard End, Hemingbrough, North Yorkshire YO8 6RJ. Cheques should be made payable to Howden Minster Appeal.