Her donation -- by far the biggest to the "No" camp -- was received "recently", an official confirmed.
Writing on her website, Rowling said while she was "no fan" of the current British government, she was afraid the Scottish economy would be destabilised by going it alone.
"My hesitance at embracing independence has nothing to do with lack of belief in Scotland's remarkable people or its achievements," she wrote.
"The simple truth is that Scotland is subject to the same 21st century pressures as the rest of the world.
"It must compete in the same global markets, defend itself from the same threats and navigate what still feels like a fragile economic recovery.
"The more I listen to the 'Yes' campaign, the more I worry about its minimisation and even denial of risks."
Rowling said she was aware some people would consider her "insufficiently Scottish" to take a view on the independence issue.
But referring to characters from her books about the boy wizard, she said: "When people try to make this debate about the purity of your lineage, things start getting a little Death Eaterish for my taste."
Rowling's donation is the largest received by the "No" campaign, while the pro-independence camp has benefited from £2.5 million from Colin and Chris Weir, a couple who won £161 million in the EuroMillions lottery in 2011.
Polls show that the "No" vote holds a clear lead over the "Yes" camp, although a potentially significant chunk of the electorate remains undecided.
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Writing on her website, Rowling said while she was "no fan" of the current British government, she was afraid the Scottish economy would be destabilised by going it alone.
"My hesitance at embracing independence has nothing to do with lack of belief in Scotland's remarkable people or its achievements," she wrote.
"The simple truth is that Scotland is subject to the same 21st century pressures as the rest of the world.
"It must compete in the same global markets, defend itself from the same threats and navigate what still feels like a fragile economic recovery.
"The more I listen to the 'Yes' campaign, the more I worry about its minimisation and even denial of risks."
Rowling said she was aware some people would consider her "insufficiently Scottish" to take a view on the independence issue.
But referring to characters from her books about the boy wizard, she said: "When people try to make this debate about the purity of your lineage, things start getting a little Death Eaterish for my taste."
Rowling's donation is the largest received by the "No" campaign, while the pro-independence camp has benefited from £2.5 million from Colin and Chris Weir, a couple who won £161 million in the EuroMillions lottery in 2011.
Polls show that the "No" vote holds a clear lead over the "Yes" camp, although a potentially significant chunk of the electorate remains undecided.
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