The Charles Rennie Mackintosh House in Northampton is one of 13 important buildings in the region to come off the Buildings at Risk register.
George Bernard Shaw slept at the Macintosh house at 78 Derngate
But English Heritage says there are still 100-plus buildings in the region in danger of falling into disrepair.
Other entries removed from the register include Freston Tower, Suffolk, and a bridge at St Pauls Walden, Herts.
There are seven new entries to the register including the Jumbo water tower in Colchester.
The Macintosh house, 78 Derngate, is one of the most important works of the famous designer still standing.
New to 'Buildings at Risk' list in the region
Martello Tower, Bawdsey, Suffolk
Oxney Farmhouse, Oxney, Peterborough
Church of St Denis, East Hatley, Cambs
Jumbo water tower, Colchester
Church of All Saints (ruin), Stanway, Essex
Dovecote, Purfleet, Essex
Barn, Bentley, Suffolk
Rennie Mackintosh totally remodelled the home of the Bassett-Lowke family in 1917.
The house opened to the public in the spring while the neighbouring property at number 80 has been converted into a visitors' centre.
Before its restoration by the 78 Derngate Northampton Trust, the house was semi-derelict and had been empty for more than 10 years.
The house was Mackintosh's only domestic commission outside Scotland.
Nick Balaam, assistant director for English Heritage in the East of England, said: "Across the region English Heritage offered grants amounting to £445,000 towards the repair of buildings on the register.
"Two of our success stories are in Hertfordshire; 173 High Street, Berkhamstead, the oldest known timber-framed shop in the country, has been taken off the 'At Risk" register following conservation and restoration works supported by a £250,000 grant from English Heritage.
Building removed from 'At Risk' register in the region
Freston Tower, Suffolk
Fornham St Genevieve church (ruin), Suffolk
173 High Street, Berkhamsted, Herts
Bridge at Hoo Park, St Paul's Walden, Herts
Pumping station, Pymore, Cambs
Mashbury Hall Chase Church, Essex
The Octagon, Hunstanton, Norfolk
Bethel Hospital, Norwich
Music Room, Earsham Hall, Norfolk
The Potteries, Great Yarmouth
Ashmans Hall, Barsham, Suffolk
Mackintosh House, Northampton
Garden house at Easton Neston, Northants
"Also the 1764 bridge in Hoo Park, St Paul's Walden, has been repaired and conserved with an English Heritage grant of £136,000."
Nationally the register shows 94 entries have been safely removed and now have a secure
The launch of the register on Wednesday heralds the start of the second series of the BBC's Restoration, which features the plight of outstanding historic buildings all over the UK, including the Bawdsey Transmitter Block, Bawdsey, Suffolk.
The Register lists nearly 1,500 of the nation's most vulnerable Grade 1 and II* heritage assets.
The list is now in its seventh year, and English Heritage said it was an invaluable measure of what the nation stood to lose if a future cannot be found for its most previous buildings.