Saudi Arabia is to give women the right to vote and run in future municipal elections, the only public polls in the kingdom.
King Abdullah has also announced that women would have the right to join the Shura Council, an advisory body, whose members are all appointed.
The changes will occur after municipal polls on Thursday.
King Abdullah announced the move in a speech at the opening of the new term of the Shura Council in Riyadh on Sunday.
''Because we refuse to marginalise women in society in all roles that comply with sharia, we have decided, after deliberation with our senior clerics and others ... to involve women in the Shura Council as members, starting from next term,'' he said.
''Women will be able to run as candidates in the municipal election and will even have a right to vote.''
A BBC correspondent says it is an extraordinary development for women in Saudi Arabia, who are not allowed to drive, or to leave the country unaccompanied.
Municipal elections are the only public polls in Saudi Arabia. Half the seats are appointed by the government.
The next municipal elections are due in four years.