In electoral systems, voter registration (or enrollment) is the requirement that a person otherwise eligible to vote must register (or enroll) on an electoral roll, which is usually a prerequisite for being entitled or permitted to vote.

The rules governing registration vary between jurisdictions. In many jurisdictions, registration is an automatic process performed by extracting the names of voting age residents of a precinct from a general-use population registry ahead of election day, while in others, registration may require an application being made by an eligible voter and registered persons to re-register or update registration details when they change residence or other relevant information changes.

Some jurisdictions have "election day registration" and others do not require registration, or may require production of evidence of entitlement to vote at time of voting. In jurisdictions where registration is not mandatory, an effort may be made to encourage persons otherwise eligible to vote to register, in what is called as a voter registration drive. In countries where resident registration is compulsory, voter registration usually does not exist, since voter eligibility can be determined from the residence register.

Even in countries where registration is the individual's responsibility, many reformers, seeking to maximize voter turnout, argue for a wider availability of the required forms, or more ease of process by having more places where they can register. The United States, for example, the National Voter Registration Act of 1993 ("Motor Voter Law") and similar laws require states to offer voter registration at motor vehicle departments (driver's license offices) as well as disability centers, public schools, and public libraries, in order to offer more access to the system. State authorities are also required to accept mail-in voter registrations. Many jurisdictions also offer online registrations.