No ordinance creates or governs the deed poll itself, and there is no Deed Poll Ordinance despite what several online guides claim. The right to change your name rests on the common law received into Hong Kong and preserved after 1997. Legislation regulates the form of the instrument and the consequences of the change, not the right. On form, the Conveyancing and Property Ordinance (Cap. 219) removed the old requirement for wax and ribbon: an instrument signed by an individual is treated as sealed if it describes itself as a deed, states that it has been sealed, or bears any mark intended to represent a seal. Delivery completes execution. Witnessing is not imposed by statute, yet an instrument attested by anybody other than a Hong Kong solicitor is routinely queried, which is why the profession treats solicitor witnessing as compulsory in substance.
The consequences run through the Registration of Persons Ordinance (Cap. 177) and the Registration of Persons Regulations (Cap. 177A), which govern the HKID and the particulars registered against it. The Director of Immigration sits as Commissioner of Registration, and an application to amend a registered name is made on Form ROP 73. The office then calls you in to produce the originals, and may require a statutory declaration before a registration officer. The Immigration Department guidance on amending the registered particulars of a Hong Kong identity card sets out the submission channels. Furnishing false information to obtain an identity card is a criminal offence, so a solicitor will decline to witness a deed where the new name looks chosen to escape a creditor.
Two statutes matter at the edges. The Births and Deaths Registration Ordinance (Cap. 174) controls the birth entry, where no alteration to a child's name may be made once the child has reached eleven, and the Guardianship of Minors Ordinance (Cap. 13) supplies the welfare principle governing parental disputes over a surname.