Twins Craig and Charlie Reid, who are well-known for hits such as Letter To America and I'm Gonna Be (500 Miles), gifted £10,000 to Yes Scotland, new figures revealed.
They said that as "lifelong supporters of Scottish independence" the cash gift was a "matter of principle" for them.
They spoke after the Electoral Commission published its latest figures on campaign donations ahead of the referendum on September 18.
The brothers said: "We are lifelong supporters of Scottish independence. For us, it is a matter of principle. We will be voting Yes for a prosperous, fair and progressive European nation."
Yes Scotland raised £168,000 in donations between July 25 and August 21 this year, with a further £10,000 being given to the pro-independence Business for Scotland group.
The main pro-UK campaign group Better Together did not receive any donations over this period, although £75,000 was donated to other organisations who want to see Scotland stay in the UK.
Better Together has already asked people to stop sending small donations to its campaign as it was inundated with cash after the first live television debate between its leader Alistair Darling and First Minister Alex Salmond.
Let's Stay Together, a UK-wide campaign urging Scots to vote No that has been backed by celebrities such as Sir Paul McCartney, received £25,000, including £15,000 from author CJ Sansom.
Meanwhile, the No Borders Campaign, which is also backing a No vote in the referendum, received £50,000 in donations between July 25 and August 21.