The writer of the Harry Potter books, who lives in Edinburgh, has publicly backed the "Better Together" campaign as the Scottish referendum in September gets closer.
Explaining her decision on her website, Rowling said there was a "denial of risks" within the "Yes" campaign.
Voters in Scotland will go to the polls on September 18 to decide on their independence from the UK.
They will be asked the "Yes/No" question: "Should Scotland be an independent country."
"My hesitance at embracing independence has nothing to do with lack of belief in Scotland's remarkable people or its achievements. The simple truth is that Scotland is subject to the same 21st century pressures as the rest of the world," Rowling said.
It must compete in the same global markets, defend itself from the same threats and navigate what still feels like a fragile economic recovery, Rowling said.
"The more I listen to the 'Yes' campaign, the more I worry about its minimisation and even denial of risks," she said.
"Whenever the big issues are raised - our heavy reliance on oil revenue if we become independent, what currency we'll use, whether we'll get back into the EU - reasonable questions are drowned out by accusations of 'scaremongering'," Rowling said.
"I also know that there is a fringe of nationalists who like to demonise anyone who is not blindly and unquestionably pro-independence and I suspect, notwithstanding the fact that I've lived in Scotland for 21 years and plan to remain here for the rest of my life, that they might judge me 'insufficiently Scottish' to have a valid view," she said.
Rowling donated 1 million pounds to the campaign.