It also supports 37,721 jobs throughout Scotland, with almost a third concentrated in Edinburgh and the Lothians, researchers found.
As well as looking at the impact of ScotRail on the tourist industry, the Fraser of Allander Institute study examined the specific contribution of key scenic routes operated by the company.
It revealed train travel directly enables 8,432 jobs in the two tourist areas covered by the West Highland Line which runs from Glasgow to Mallaig via Oban and Fort William.
The line has three times been voted the world's top rail journey by subscribers to Wanderlust travel magazine.
A total of 42 million passengers travelled on ScotRail trains for leisure trips throughout the country during 2012, the study said.
It found ScotRail adds an annual £1.22 billion worth of GDP, a measure of a country's economic activity, in the Scottish tourism industry.
It also looked at the operator's role in future events such as this month's Commonwealth Games in Glasgow and the Ryder Cup at Gleneagles in September. The institute, part of the University of Strathclyde, found these will further boost its economic impact on tourism.
It said ScotRail, part of Aberdeen-based FirstGroup, expects to provide 1.1 million rail trips to people attending the Games and anticipates transporting around 40,000 spectators to and from the golf tournament.
Transport Minister Keith Brown welcomed the report and said Scotland's railways are "enjoying a massive resurgence in popularity".
"We want to capitalise on the undoubted potential for tourism across the many routes across Scotland and encourage operators to come forward with proposals to promote and facilitate the development of tourism using the rail network, as well as enhancing the scenic opportunities for passengers to make our rail journeys as good as our marvellous destinations," he added.
The findings also revealed the tourist industry in Scotland directly supports an estimated 167,000 jobs and £5.4 billion worth of GDP.
Tim O'Toole, chief executive of FirstGroup, said: "Tourism matters and people should recognise that in the Scottish rail franchise we have a very high-performing economic asset. We should not relent in making it better but also recognise the job our people are doing every day."
Steve Montgomery, managing director of ScotRail, said: "The report outlines the scale of the contribution the company makes, not just in economic terms but also via the major advances we've made since taking over the franchise. That includes major investment in enhancing services and facilities across the country and the great strides we've made in areas such as our environmental performance and our community activities."