The Scottish player sent out a post on Twitter just hours ahead of the polls opening on the referendum to break away from the United Kingdom.
Murray indicated that negative campaigning by the anti-independence side made up his mind in favour of secession.
He tweeted to his 2.7 million followers: "Huge day for Scotland today! no campaign negativity last few days totally swayed my view on it. excited to see the outcome. lets do this!'
The 27-year-old Murray, who grew up in Dunblane, Scotland, resides in England and is not eligible to vote in the referendum. But he is one of Scotland's most high-profile global figures, and his words got wide airing in the country.
Later Thursday, Murray was quoted as telling the Daily Mail website he would continue to represent Britain in the 2015 Davis Cup, regardless of the outcome of the referendum. If Scotland does vote to break away, independence would not go into effect until March 2016.
Britain was drawn on Thursday to face the United States in the first round of next year's Davis Cup. Led by Murray, Britain beat the Americans 3-1 last year in the first round in San Diego; the 2015 rematch will be in Britain from March 6-8.
"I will be playing for Great Britain in the Davis Cup next year. That is for sure," Murray was quoted as saying before the draw on the Mail's website. "As far as I'm concerned the vote doesn't change anything in that regard."
In 2013, Murray became the first British player in 77 years to win the Wimbledon men's title, a victory that was celebrated with national fervour. He also won a gold medal for Britain at the 2012 London Olympics, draping himself in the Union Jack after beating Roger Federer in the final.
"If Scotland became independent, then I imagine I would be playing for Scotland," Murray told reporters at the recent U.S. Open.
However, questioned repeatedly in recent years and months about independence, Murray steadfastly refused to come out for one side or the other. He was mindful of the reaction he received in England when he said — jokingly — that he would support "anyone but England" at the 2006 World Cup.
"I don't know a whole lot about politics, and I have made that mistake in the past and it's caused me a headache for seven or eight years of my life and a lot of abuse," he said.
Murray spoke to the Daily Mail about his decision to send the early morning tweet on Thursday.
"I've followed pretty much everything about it (the independence debate) over the last two weeks, and especially in the last few days. and that's how I felt at the time," he said.
'It's not my decision. I can't vote. It's for the Scottish people to decide, and I trust them to make the right decision. I will support whatever the outcome is. Regardless of how it goes, it's very important for everyone to come together and stick together afterwards."
After Murray's Wimbledon victory, Scottish First Minister Alex Salmond waved the "Saltire," the blue and white Scottish flag, in the Royal Box.
Murray was critical of Salmond's gesture and spoke of his national identity.
"I am proud to be Scottish, but I am also proud to be British," he said at the time. "I don't think there is any contradiction in that."
It's uncertain whether Scotland would be able to form an independent team in time for the 2016 Olympics in Rio de Janeiro. If not, Scottish athletes could either continue to compete for Britain or compete under the Olympic flag.