Ar 24 Rhagfyr 2020, saith diwrnod cyn diwedd y cyfnod pontio, daeth y trafodaethau i ben, daeth yr UE a'r DU i gytundeb, ac yna cafodd Cytundeb Masnach a Chydweithredu'r DU/UE ei gyhoeddi. Roedd y Datganiad Ysgrifenedig gan y Prif Weinidog ar 24 Rhagfyr 2020 yn nodi ymateb uniongyrchol Llywodraeth Cymru i'r cytundeb. Er ein bod yn croesawu'r ffaith bod y DU wedi osgoi canlyniad anhrefnus heb gytundeb, mae'r cytundeb yn un gwan iawn gyda rhwystrau newydd sylweddol i fasnachu a lefelau sylweddol is o gydweithrediad â'r UE ar draws nifer o feysydd pwysig, gan gynnwys diogelwch.
On 24 December 2020, seven days before the end of the transition period, the negotiations concluded, a deal between the EU and UK was agreed, and the UK/EU Trade and Cooperation Agreement (TCA) was subsequently published. The Written Statement from the First Minister on 24 December 2020 set out the Welsh Government’s immediate response to the deal. While welcoming the fact the UK had avoided a chaotic no-deal outcome, the deal is a very thin one with considerable new barriers to trade and significantly reduced levels of cooperation with the EU across a number of important areas, including security.