Ukraine's newly empowered parliament also fired the country's despised interior minister and voted to free Yulia Tymoshenko, the former prime minister who has spent more than two years in jail for what supporters say are politically tainted charges.
It was not clear, however, how well the deal would go down with all the sides involved in Ukraine's protracted political crisis.
A senior Russian lawmaker immediately criticised it as being crafted for the West, and Ukrainian protesters angry over police violence showed no signs of abandoning their sprawling encampment in central Kiev.
Within hours of the signing, Ukraine's parliament voted to restore the 2004 constitution that limits presidential authority, clawing back some of the powers that President Viktor Yanukovych had pushed through for himself after being elected in 2010.
Also Read
The next order of business was Tymoshenko. Legislators voted 310-54 to decriminalise the count under which she was imprisoned, meaning that she is no longer guilty of a criminal offense.
"Free Yulia! Free Yulia!" legislators chanted after the vote.
It's not immediately clear when she might be released from the jail in the eastern city of Kharkiv.
Three European foreign ministers spent two days and all night trying to negotiate an end to the standoff, which began when Yanukovych decided not to sign a pact with the European Union in November in favor of having closer ties with Russia.