The bill put forward by Labour MP Yvette Cooper to extend Article 50 in a bid to avoid a no-deal Brexit has received royal assent and become law.
MPs and peers backed the bill on Monday night meaning there is now a legal requirement on Theresa May to seek an extension to Article 50 to prevent a no-deal Brexit.
The new law that requires the prime minister to extend the Brexit process to avoid no-deal.
The Commons backed a series of Lords amendments to the European Union (Withdrawal) (No 5) Act after it was rushed through both Houses of Parliament.
The bill was amended by peers to state that nothing in it prevented the prime minister from “seeking or agreeing” an extension, providing it was not earlier than May 22.
Mrs May is already seeking a further Brexit delay to June 30 and EU leaders will discuss this at an emergency summit on Wednesday.
Writing on Twitter, Ms Cooper said: “Parliament has voted tonight against the damage & chaos that no deal would cause for jobs, manufacturing, medicine supplies, policing & security.”