The law provides for the new seats to be allocated to parties in parliament in proportion to their number of elected representatives.
It is in keeping with Prime Minister Begum Khalida Zia's promises to gradually increase women's representation in the legislative assembly.
The main opposition Awami League, led by Shaikha Hasina, boycotted the parliamentary vote, but the law was passed by 226 votes in favour to one against, officials said.
Both the prime minister and the opposition leader are women, but there are only five other female lawmakers at present.
Parliament starts a new session in June, and the law providing for the new seats will be valid for 10 years.
Bangladesh had 30 nominated women legislators until the law governing their appointment expired just before the last election in October 2001.
The Awami League and various women's rights groups have opposed the creation of reserved seats, demanding that women should be made members of parliament through direct voting in national elections.