The move was revealed in the Scottish government's infrastructure and investment plan last week, which outlines up to £60 billion of spending on infrastructure up to 2030.
The plan estimates that completing a high-speed rail route from Manchester to Glasgow, including building new stations, will cost £15 billion. The Scottish government is promising to pay for the line north of the border.
However, the pledge is based on the UK government approving the line in England and it is uncertain where the money will come from as it is allocated for spending rounds from 2020. The current spending round ends in 2015.
Scottish ministers will continue to press for the High Speed 2 (HS2) rail scheme to come to Scotland "at the earliest opportunity", the plan says, although final decisions on the route rest with Westminster.
UK transport secretary Justine Greening has delayed making her decision on plans for the first phase of the high-speed line, set to run between London and Birmingham, until January. If the proposals are approved, a second phase could see the line going to the north of England and then potentially to Scotland.
But the exact route is yet to be decided with HS2 Ltd, the company set up by the Department for Transport to develop the line, still considering the options for routes to Manchester and Leeds.
The Scottish government has based its plan on a route going via Manchester to Glasgow. A spokesman said: "We need Westminster to commit to linking up Birmingham and Manchester before we can take this forward. We have long been pressing the case that it is vital for a high-speed rail network to be established across Britain.
"We are ready to start preparatory work and we have already asked the secretary of state for transport that the remit of HS2 Ltd is extended to include detailed planning for routes to and within Scotland."
The Scottish government's infrastructure plan also commits to improving motorway and dual carriageway links, electrifying rail lines, investing in schools and hospitals, and measures aimed at making homes more energy efficient.
Alex Neil, cabinet secretary for infrastructure and capital investment, said the plan identified investments that will "deliver growth, support jobs and keep our economy moving" despite cuts to Scotland's capital budget.
However, the Scottish Labour party dismissed the Scottish National Party (SNP) government's plan as a "wish list".
Scottish Liberal Democrat leader Willie Rennie said there was no detail on how the link could be funded if Scotland leaves the UK. "Given the lack of answers from the SNP on independence, none of the plans can be taken seriously after this parliament," he said.
The plan can be viewed via Planning Resource.co.uk/go/referencesection
Capital Spending Boost
Total estimated capital investment in Scotland 2011-15
Source: Scottish government
£2.8bn - 2011/12
£3.2bn - 2012/13
£3.3bn - 2013/14
£3.5bn - 2014/15