The deal negotiated by Sufi Mohammad has been well received in Swat
Pakistani President Asif Zardari will sign an order implementing Sharia law in Swat valley only once peace there is fully restored, his office says.
President Zardari's spokesman said that this would require the laying down of arms by Islamic militants.
Meanwhile, pro-Taleban cleric Sufi Mohammad has arrived in the Swat valley to try to convince local Taleban leaders to agree to the deal.
Locals have largely welcomed it but critics say it is unacceptable.
Sufi Mohammad is the father-in-law of Maulana Fazlullah, the current head of the Taleban in Swat.
Mr Mohammad's TNSM party has already signed the deal to implement Sharia with the government of North West Frontier Province (NWFP).
The deal has been welcomed by locals in the region. Hundreds turned out to greet Sufi Mohammad as he arrived in Mingora, the largest town in the Swat valley.
But critics - especially in the US - have expressed concern over what they see as capitulation to the Taleban.
They believe introducing a separate system of justice sets a dangerous precedent for other militias in parts of Pakistan.
Information Minister Sherry Rehman denied the government had made any "concession".
"It is in no way a sign of the state's weakness. The public will of the population of the Swat region is at the centre of all efforts and it should be taken into account while debating the merits of this agreement," she said.
"The president will approve the Nizam-e-Adal Regulation after the restoration of peace in the region."
Sufi Muhammad arrived in Mingora with a caravan of some 300 vehicles - a day after he agreed to the truce with the NWFP government. Hundreds of people lined the route, waving and cheering the procession.
He has pledged not to leave Swat until peace is secured.
"We are happy. People are welcoming us," Swat resident Shah Wali, who was travelling with the motorcade, told The Associated Press news agency.
Correspondents say that many in the caravan wore black turbans - a Taleban trademark.
On Monday regional officials urged the Taleban to lay down their arms permanently, a day after the militants agreed a 10-day truce.
Once one of Pakistan's most popular holiday destinations, the Swat valley is now mostly under Taleban control.
Thousands of people have fled and hundreds of schools have been destroyed since the Taleban insurgency in 2007.
NWFP Chief Minister Ameer Hussain Hoti said on Monday that a bill had been signed that would implement a separate system of justice for the whole region.
Many took the day off to welcome the deal
The BBC's M Ilyas Khan, who was recently in Swat, says the Taleban had already set up their own version of Islamic justice.
The NWFP government now hopes that a grand jirga (council) led by Sufi Mohammad will be able to persuade all the factions to comply.
The Taleban have said they will examine the document before ending hostilities permanently.
More than 1,000 civilians have died in shelling by the army or from beheadings sanctioned by the Taleban. Thousands more have been displaced.