Secretary of State Ross Miller says Douglas County was the last of Nevada's 17 counties to come online Friday.
To register online, people need to be at least 18 years old and have a Nevada driver's license or identification card issued by the Department of Motor Vehicles. During the application process, the signature on file with the DMV is applied to the voter's registration record.
The system was launched in Clark County, the state's population hub, in 2010.
But now voters statewide can access their voting information through the secretary of state's website and update their address or change party affiliation.
Statewide, the project cost $248,000. It was federally funded through the Help America Vote Act.