Published on the local government's official Facebook page on Wednesday, the decree states that women and men should enjoy "equality... in all walks of public and private life."
Last year, Syria's Kurds created autonomous governments in the three regions where they are a majority, establishing self-proclaimed rule.
Arabs also hold office, and the decrees apply to all ethnicities living in the self-governing areas.
The decree, passed by the leaders of the Al-Jazira canton – officially Hasakeh province – stipulates that women have the right to equal labour rights, including pay.
Women must be 18 years old to marry, and they are cannot be married off without their consent.
"Polygamy is forbidden," the decree states, adding that women have the same right to bear witness in court as men, and that they have full inheritance rights.
In Islam, men are allowed four wives on condition that they can afford it, while women have limited inheritance rights and fewer rights before a law court.
According to the Syrian Observatory for Human Rights, Syrian Kurds have not so far allowed women to inherit at all.
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The decree bans so-called "honour killings" and "violence and discrimination" against women and says women must get paid maternity leave for their first three children.
"'Polygamy is forbidden,' the decree states"
According to the Britain-based Observatory, the decree is an "affront to laws being passed by the Islamic State (IS), which are highly discriminatory against women."
Observatory director Rami Abdel Rahman told AFP: "While fighting the jihadists, the Kurds also want to send a message to the international community, to say that they want to espouse a culture of democracy and civil rights."
Backed by rebels, the Iraqi peshmerga and a US-led coalition, Syria's Kurds are fighting a fierce battle against the IS jihadists in the flashpoint town of Kobane on Syria's border with Turkey.
More than 1,000 people, mostly IS fighters, have been killed there in less than two months, most of Kobane's residents have fled. The town has become a symbol of resistance against the jihadists.
Abdel Rahman called the Kurdish decree "a major step for the region, whose tribal society has long been ruled by conservative social mores."
Damascus does not recognise the self-proclaimed governments established by the Kurds in 2013.