Interior minister Abdoulaye Daouda Diallo yesterday said that 62.9 per cent voted "Yes" on constitutional reforms while 37.1 per cent voted against it.
Turnout was 40.42 per cent of eligible voters, he told a press conference.
The official referendum results will be published on Friday by the country's electoral commission and require constitutional court approval.
President Macky Sall was elected in 2012 partly on a platform to reduce the presidential mandate from seven years to five.
Also Read
But Senegal's top court rejected his proposal in February, triggering the referendum to allow the reforms to come into force once Sall leaves office.
Opposition parties and several civil society groups urged a "No" vote, arguing that Sall reneged on his promise to leave office early and criticising the referendum as a cop-out.
The referendum became a de facto Yes/No vote on Sall's popularity, eclipsing more than a dozen other proposed points of reform to the constitution.