St Magnus Episcopal Church in Lerwick will be restored with the help of a £12,000 grant from the council.
Members of the SIC’s planning committee agreed the move when they met at the Town Hall on Wednesday.
The money will form part of a financial package that will enable the church to undertake a comprehensive programme of conservation and repair works.
Developers will be asked to strip all roof pitches and re-cover with Scotch slate.
Stonework repairs will be carried out as part of the restoration and stained glass windows will also be repaired.
Rainwater goods, such as drainpipes, will be replaced in cast iron.
The maximum grant available from the council is generally £5,000.
However because of the architectural and historic interest of the building, and the scale of the cost of works proposed – expected to amount to £435,000 – councillors agreed to make a £12,000 payment as recommended by officials.
The grant can be made from the existing conservation grant budget.
A report before the committee held the church as one of the finest ecclesiastical buildings in Shetland.
It was designed and built in 1862-64 by Alexander Ellis of Aberdeen, with the distinctive bell tower – also by Ellis – added in 1891.