Dong Sun is an elected member of the Committee for the Technology and Innovation Constituency. During the 2021 Hong Kong legislative election, Sun was elected to the 7th Legislative Council of Hong Kong for the Election Committee (constituency).
Sun has advocated for Hong Kong's development as an international science and technology centre, creating synergistic development with the Greater Bay Area. Sun has promoted the “Matrix Model of Science and Technology Innovation", calling for an integrated science and technology ecosystem supporting impactful scientific research, accelerated technology transfer, and the strengthening of competitive industries.
In January 2022, Sun was one of three people, out of 90 legislative council members, who took his oath using Mandarin rather than the local language, Cantonese.[2]
In June 2022, Sun was appointed Secretary for Innovation, Technology and Industry of the HKSAR Government, assuming office on 1 July 2022, making him the first bureau secretary of Hong Kong from mainland China.
On 8 October 2022, Sun defended the LeaveHomeSafe app, and said "We use the LeaveHomeSafe app system to support the government's anti-pandemic policies very successfully."[3] In contrast, a government pandemic advisor, David Hui, said the app should stop being used.[4]
On 23 October 2022, Sun warned that Hong Kong was lagging behind other cities and said the next few years will be Hong Kong's last chance to become a global innovation and tech hub.[5]
In November 2022, Sun met with employees of Google and "mounted solemn negotiations" about the search engine's ranking of Glory to Hong Kong.[6] Sun requested that Google "remove wrong information from the search results."[7] In March 2023, Sun said "We have been in negotiation many times hoping it would remove the wrong information, but it is regrettable that it has not taken corresponding measures."[8]
In July 2023, Sun said that Google had asked him to provide proof that Glory To Hong Kong was illegal, and therefore the Hong Kong government filed a motion to make it illegal; Sun said "Very well, since you brought up a legal issue, let’s use legal means to solve the problem."[9] In July 2023, the High Court rejected the proposed ban on the song.[10]
In August 2023, Sun said that he had "suffered a lot of pressure" from Kenneth Lau, over Lau's insistence to integrate villages into the San Tin Technopole plan.[11]