Alastair Graham gifted £300,000 to Edinburgh's Morningside Parish Church.
Mr Graham, from Edinburgh, died in February this year at the age of 94 after spending years building up his own accountancy firm.
Details have now emerged of the £1,274,000 fortune he amassed.
Alastair left instructions for the charity Capability Scotland to receive £600,000. He also gifted £300,000 to the Dog Aid Society of Scotland.
Mr Graham asked that his gift for Morningside should be used to help maintain the church and fund repair works.
Reverend Dr Derek Browning of Morningside Parish Church said: "We are grateful for this generous donation."
Mr Graham's published will revealed he left £74,000 to friends including £30,000 to his business partner of 30 years, James Brown. But the batchelor ordered the bulk of his estate to be handed over to good causes.
Capability Scotland Chief Executive, Dana O'Dwyer, said: "It was wonderful to find out that Capability Scotland has been left such a significant sum of money.
"Gifts such as really make an impact on what we can achieve through our work supporting disabled people in Scotland."