A one-person company is not one fixed legal form. Across countries it ranges from trading in your own name with no legal separation, to a registered company with a single member, director, or shareholder.
What "one-person company" means in law
The term appears formally in India: the Companies Act 2013 defines a "One Person Company" as a company which has only one person as a member (India Code, s.2(62)). China's Company Law (2023 revision) lets a limited liability company be formed by one to fifty shareholders, so a single shareholder may form one (National People's Congress, Article 42). In most other places the same idea sits under different names — sole proprietorship, single-member LLC, or a one-director, one-shareholder private company.
Australia
Trading in your own name: you operate as a sole trader, the simplest structure, and it is relatively easy and inexpensive to set up (business.gov.au). The owner is legally responsible for all aspects of the business, including debts and losses.
Incorporating: you form a company that is a separate legal entity. As a member you are not liable for the company's debts beyond any amount unpaid on your shares (business.gov.au). The rule is set by the Australian Government (Department of Industry, Science and Resources).
UK
Most businesses register as a sole trader or a limited company (GOV.UK). A limited company is legally separate from its owners and is run by one or more directors — so one person can be the sole director and sole owner. The rule is set by GOV.UK.
US
An unincorporated business owned by one person is a sole proprietorship; the IRS defines a sole proprietor as someone who owns an unincorporated business by themselves (IRS). An LLC is created under state statute, and most states permit single-member LLCs (IRS). A sole member of a domestic LLC that elects corporate treatment is not a sole proprietor. The rules are set by the Internal Revenue Service and by each state's statute.
Singapore
A sole proprietorship has only one owner and no legal split between you and the business, so you are fully liable for all debts and losses (ACRA). A company is a separate legal entity offering the most personal protection, but it carries the most rules and the most yearly paperwork (ACRA). The framework is set by the Accounting and Corporate Regulatory Authority (ACRA).
India
The Companies Act 2013 gives "One Person Company" a formal definition: a company with only one person as a member (India Code, s.2(62)). This is the one jurisdiction in this list where the one-person form is named directly in the statute. The rule is set by the Legislative Department, Ministry of Law and Justice, Government of India.
China
Under the Company Law (2023 revision), a limited liability company is formed by capital contributions from one to fifty shareholders, so one shareholder may form one (National People's Congress, Article 42). Separately, citizens with business capacity who register as individual businesses (个体工商户) are governed by the State Council's Regulations on Promoting the Development of Individual Businesses (State Council). The rules are set by the National People's Congress and the State Council.
Hong Kong (brief note)
Every private company must have at least one director who is a natural person (Hong Kong Companies Registry, citing Companies Ordinance Cap. 622 s.457(2)). A one-person private company is therefore possible with a single individual director.
How to choose and what to check
Pick the form that matches how much personal liability you can carry and how much paperwork you will keep up with. A sole structure is simplest but leaves you fully liable; a company separates you from the business but adds filings and rules. The exact steps, fees, and treatment differ by jurisdiction and change over time — confirm the current position with the official body named above and with a qualified local professional before you register.