Egypt's new constitution was approved by 63.8% of voters in a two-round referendum, the supreme election committee said on Tuesday.
The result, which followed voting on 15 and 22 December, matched an earlier unofficial tally given by Muslim Brotherhood.
"We have seriously investigated all the complaints," said judge Samir Abu el-Matti of the Supreme Election Committee on Nile News TV. The final official turnout was 32.9%.
The draft document was backed by President Mohamed Mursi.
The BBC reports elections must now take place within two months.
Critics say the document betrays the revolution that toppled President Hosni Mubarak in February last year.
Mr Mursi's supporters say it will secure democracy and encourage stability.