The official Gulf News Agency said 196,262 out of 217,000 eligible Bahrainis over the age of 20 - or about 90% - had voted in the two-day referendum which ended on Thursday.
Figures released by the Justice Ministry said more than 98% of voters backed the reforms, which are due to be implemented by 2004.
The reforms would put Bahrain in a class of its own in the oil-rich region, where absolute rulers are the norm and political freedoms are highly restricted.
Women would be able both to vote in parliamentary elections and stand for office - another first for the region.
The official Gulf News Agency said 196,262 out of 217,000 eligible Bahrainis over the age of 20 - or about 90% - had voted in the two-day referendum which ended on Thursday.
The agency reported that the country's ruler, Sheikh Hamad bin Issa al-Khalifa, said he was "honoured" by the result.
"We have pledged in the charter to establishing a bicameral system and the holding of general elections for the representative chamber in order that democracy comes in harmony with the formula of a kingdom," his statement said.
Partial restoration
The national charter should give Bahrain its first elected parliament since 1975, when Sheikh Hamad's late father dissolved a chamber that had come into being two years earlier.
An independent legislature has been a key demand of Bahrain's Shi'a majority, which has had had almost no political power since the parliament was dissolved.
The Shi'a mounted violent opposition to the Sunni ruling class in the 1990s.
Nearly 40 people were killed in riots, bombing and arson between 1994 and 1999.
Reformist ruler
Sheikh Hamad al-Khalifa succeeded his father, Sheikh Issa in 1999 and he has moved towards reform since then.
He has released hundreds of political prisoners, the last batch on the day before polling.
The atmosphere was one of celebration at polling stations, as men and women queued - in separate lines - to cast their votes.
"A parliament will open the doors to democracy", a voter in a predominantly Shi'a village said after voting.
"It will give the people a chance to participate in building their country", he added.