Vyner Brooke announced his intention to cede Sarawak to Britain in early 1946. The British government sent two Malay-speaking Members of Parliament to Sarawak to ascertain whether the people were in favour of cession. It was found that there was sufficient support for cession to be put before the Council Negri. This motion was subsequently debated for three days in the Council Negri. The Bill of Cession was read for the third time on 17 May 1946 and was passed by 19 votes against 16.

Rajah Vyner Brooke signing the Instrument of Cession at the Astana, Kuching, May 1946.

On 1 July 1946, Sarawak became a British Crown Colony with Sir Charles Arden Clarke made the first British Crown Colonial Governor.

The people of Sarawak were largely divided over the question of cession. The passing of the motion by a small European majority in the Council Negri did not end this issue. Dissatisfaction mounted and culminated in the mass resignation of the 388 Malay civil servants and the assassination of Sir Duncan Stewart, the Second British Governor in 1949 by Rosli Dhoby in Sibu. This marked the awakening of the political consciousness of the people of Sarawak. The British reaction to this attack was swift and the protest movement virtually died out by 1950.

The Council Negri remained as the governing body of the state. In 1956, a new constitution was promulgated. It gave an official majority tothe Council Negri for the first time. The first direct local government elections were held in November that year.