[7][8] On 22 May 2019, acting on the recommendation of the independent Judicial Officers Recommendation Commission, the Chief Executive announced Poon's appointment as Chief Judge of the High Court (a post which had become vacant upon the appointment of Andrew Cheung as a Permanent Judge of the Court of Final Appeal in October 2018), subject to the endorsement of the Legislative Council in accordance with Article 90 of the Basic Law.
[9] Pending the Legislative Council's endorsement, Poon was appointed as Acting Chief Judge of the High Court on 1 August 2019.
[11] In January 2021, Poon ruled that all three methods of building land under the Small House Policy were completely legal, overturning an earlier decision in 2019.
[12] Poon told the plaintiffs, Hendrick Lui Chi-hang and Kwok Cheuk-kin, that they did not have sufficient standing to bring up the case because they do not own land rights in the New Territories.
[13] In October 2022, Poon was part of a team of 3 judges who ruled against Jimmy Lai and said that "despite its importance to the freedom of the press, the protection afforded to journalistic material is not absolute.