The next parliamentary session wil be doubled to two years, and the Queen's Speech will be cancelled in 2018, to give MPs more time to deal with Brexit.
The longer parliament will provide "enough time to fully consider the laws required to make Britain ready for Brexit", including the Great Repeal Bill, the Prime Minister's Office said.
"Whilst our top priority right now is supporting the victims of the terrible tragedy at Grenfell tower, we also need to look ahead by setting out a legislative programme that not only delivers a successful EU exit but also a domestic agenda which aims to tackle the social injustices in our country," said leader of the commons Andrea Leadsom.
"The UK will spend the next two years preparing for our departure from the European Union in a way that best places us to realise the opportunities ahead and build a fairer society.
"This will require substantial amounts of legislation, beginning with the Great Repeal Bill."
Leadsom added: "We will build the broadest possible consensus for our Brexit plans and that means giving Parliament the maximum amount of time to scrutinise these bills by holding a two-year session of Parliament.
"It will mean we can work together to deliver a successful Brexit deal and a strong social legislative programme that delivers justice and opportunity to everyone."
This year's Queen's Speech has been delayed, to give the Conservatives more time to hammer out a deal with the DUP.