Scotland exports four times as much to the rest of the UK as it does to the EU.
Official figures show that Scottish businesses sent goods and services worth £49.8billion south in 2015, compared with £12.3billion to the continent.
The statistics will be seen as a blow to arguments that independence would be economically preferable to a hard Brexit.
The SNP’s Joan McAlpine insisted the figures showed access to the single market was “vital for jobs, household incomes and Scottish businesses”.
But the Scottish Conservatives’ finance spokesman Murdo Fraser said they proved Nicola Sturgeon’s party “would put jobs and trade at risk simply because they don’t like the United Kingdom”.
The figures also reveal Scotland exported more to non-EU countries – £16.4billion – than those in the continental bloc.
The £49.8billion worth of exports to the UK in 2015 is a 4.4% increase – or £2.1billion – on 2014, while exports to the EU also rose by £520million.
Mr Fraser said: “These are the Scottish Government’s own figures – which makes it all the more astonishing that the SNP is determined to ignore them by continuing its ideological pursuit of separation.
“The Nationalists would put jobs and trade at risk simply because they don’t like the United Kingdom.
“We have had it confirmed again – the UK is four times as important to Scotland as the EU in trade, and the SNP must recognise this immediately by ditching its unwanted and divisive plan for a second referendum on independence.”
Scottish Labour leader Kezia Dugdale said the figures showed Scotland’s “two nationalist governments” are “more interested in dividing us than protecting jobs and the economy”.
She added: “Tory plans for a hard Brexit risk damaging Scotland’s economy – but the SNP government’s own figures show that independence would be considerably worse.
“These figures confirm that the UK single market is four times more important to Scottish jobs and the economy than the EU single market.
“It is simply a reckless Nationalist gamble to put access to the UK single market, and all the jobs that depend on it, at risk.
“That’s why the SNP must drop plans for a second independence referendum.”
But Ms McAlpine said: “Scotland’s membership of the single market – which is around eight times bigger than the UK market alone – is vital for jobs, household incomes and Scottish businesses.
“This new research shows how many small businesses would be directly affected by leaving the single market, and all of the barriers to trade that would inevitably mean.”