The Queen will sign the Article 50 Bill into law on Thursday, clearing the way for Theresa May to formally start Britain's divorce from the European Union.
The European Union (Notification of Withdrawal) Bill was passed by MPs and peers on Monday with Royal Assent expected at 11am GMT.
It will then be open to the prime minister to notify Brussels that the UK is leaving the EU, starting the two-year countdown to Brexit.
Mrs May promised on Tuesday to come to the Commons later this month to announce when she had triggered Article 50, the legal mechanism for withdrawal.
She revealed in October that it would be done by the end of March.
The move comes after ministers were accused of "driving towards a cliff-edge with a blindfold on", as Brexit Secretary David Davis admitted they have made no assessment of the economic implications of failure to secure a deal with the rest of the EU.
The prime minister has declared her readiness to walk away from Brexit negotiations without agreement, insisting that "no deal is better than a bad deal".
European Council president Donald Tusk said the signals coming from the UK Government just weeks ahead of the start of negotiations amounted to "threats", but insisted Brussels would not be "intimidated".
Failure to reach agreement on a future UK-EU relationship would be worse for Britain than for the remaining 27 states, he told the European Parliament.
Mr Davis tried to ease tensions with Brussels, urging colleagues to ensure future comments about the upcoming negotiations are "as calm as possible and as amicable as possible".