Cheung was later enrolled to the Chinese University of Hong Kong, studying Politics and Public Administration. He became the president of the Student Union in 2014 and the member of the Hong Kong Federation of Students (HKFS). He was actively involved in the massive Occupy protests in 2014 against the Beijing's decision on the framework of the 2017 Chief Executive election. He became one of the nine leading figures arrested in 2017 for initiating the illegal assembly.