The judgement means Tory Prime Minister Theresa May cannot begin talks with the EU until MPs and peers give their backing – although this is expected to happen in time for the government’s 31 March deadline.
But the court ruled the Scottish Parliament and Welsh and Northern Ireland assemblies did not need a say.
The British government will make a statement to MPs later on Tuesday.
During the Supreme Court hearing, campaigners argued that denying the UK Parliament a vote was undemocratic.
But the government said it already had the powers to trigger Article 50 of the Lisbon Treaty – getting talks under way – without the need for consulting MPs and peers.
The judges rejected the case put by ministers by a majority of eight to three.
Attorney General Jeremy Wright said the government was “disappointed” but would “comply” and do “all that is necessary” to implement the court’s judgement.