The legislation was approved after the House of Lords decided to back down after its five amendments were rejected by the House of Commons.
The UK is to leave the bloc on 31 January, after which a transition period will start, envisioning negotiations on the post-Brexit trade cooperation.
The British people voted to leave the European Union in a 2016 referendum. The political chaos that followed sparked major divisions in the country, and fears that Scotland may seek to leave the UK in order to remain in the EU, as well as concerns over the fate of the common border between Ireland and Northern Ireland. Brexit also led to the resignation of Prime Minister David Cameron and his successor, Theresa May. UK Prime Minister Boris Johnson has repeatedly vowed to "get Brexit done" to be able "to move forward together."