Wallace Hartley has become part of the ship's legend after leading his fellow musicians in playing as the doomed vessel went down, most famously the hymn Nearer My God To Thee.
Hartley and his seven fellow band members all died in the tragedy in 1912, in which 1,500 people were killed after the ship hit an iceberg.
His violin, which had been a gift from his fiancee Maria Robinson, was apparently found in a case strapped to his body when it was recovered from the icy Atlantic waters.
Its re-emergence in 2006, when it was reportedly discovered in an attic in Yorkshire, prompted heated debate over its authenticity.
Titanic specialist auctioneers Henry Aldridge and Son insist nearly seven subsequent years of research and tests have proved it to be the genuine article.
Now the violin - accompanied by a leather luggage case initialled W. H.H. - went under the hammer with a host of other items from the ship at the public auction in Devizes, Wiltshire.
The violin had a reserve price of between £200,000 and £300,000 and was expected to reach as much as £400,000 - however no one expected the instrument to fetch nearly £1 million.
The previous record sale saw a 32-foot plan of the Titanic used in the inquiry into the sinking in 1912 fetch more than £220,000 two years ago.
The violin has been on exhibition since May at Titanic Branson and Titanic Pigeon Forge in the United States, the largest Titanic museums in the world where more than 315,000 viewed it and later at Titanic Belfast, the award winning visitor attraction in Northern Ireland.
Earlier this week, Andrew Aldridge, a valuer with the auctioneer, took the violin to Mr Hartley's hometown of Dewsbury, Yorkshire.
Around 200 people packed out the Henry Aldridge and Son sale room in the hope of capturing a piece of history. Many stood at the back of the room as there were not enough chairs.
Many of the lots, such as photographs, newspapers and crockery, were sold for between £10 and a few hundred pounds.
Among the unusual items sold was a violin prop from the 1997 eponymous Hollywood blockbuster starring Leonard DiCaprio and Kate Winslet.
But many of the people present had come to catch a glimpse of Hartley's violin before it went under the hammer.
There was tension in the room as principal auctioneer Alan Aldridge, Mr Aldridge's brother, started the bidding at just £50 for the violin, which was lot 230 of 251.
There were laughs from the audience but Mr Aldridge revealed that he was starting it that low so that two of his friends could bid.
Within a couple of minutes bidding had broken £100,000 had soon passed the world record of £220,000 as the competition between four telephone bidders hotted up.
There were gasps from the audience as the price reached £350,000 and then raced to £600,000. The room fell silent when bidding hit £750,000.
The violin eventually sold for £900,000 after fierce bidding between two telephone bidders. Selling the violin had taken just 10 minutes.
Alan Aldridge said that with the buyer's premium and VAT, the price would top £1 million, which he did not think would be broken.
"The record for an individual item was £220,000 and we once sold a collection for £400,000," he said.
"I don't think this price will ever be beaten. The violin was the most iconic item we have seen and there were some very, very wealthy people bidding."
Mr Aldridge said there had been some strong bidding from both British and US collectors but would not reveal who had won.
"It was an anonymous bidder," he said.
"We estimated between £200,000 and £300,000 but we always said it had the potential to hit £1 million.
"It is the only piece of Titanic memorabilia that has the potential to reach £1 million - it is so, so iconic."
Peter Boyd-Smith, a Titanic historian and seller of the ship's memorabilia, said he believed the violin had been bought by a British collector.
"I have been to many, many auctions but I have never seen one like this," he said.
"£900,000 for a violin? Absolutely incredible. It's staying in the UK and I think it is a private collector - not too sure.
"It's a world record for a Titanic artefact. The only other items that are probably worth that kind of money are the items salvaged from RMS Titanic if they are ever put up for sale and those are in the exhibitions that go around America and Europe.
"It may never get beaten."
Mr Boyd-Smith, who runs a ship and aviation antique shop called Cobwebs in Southampton, described himself as "very pleased" having successfully bid for several pieces of memorabilia.