President Kiir is expected to travel to Khartoum to sign the final agreement at a ceremony on Sunday.
The peace agreement focuses on governance and security between the warring parties.
Present at the signing ceremony were Sudanese President Omar Bashir, Kenyan President Uhuru Kenyatta, Ugandan President Yoweri Museveni, Djibouti President Ismaïl Omar Guelleh and other regional and global representatives.
Thousands of South Sudanese were massed outside the Friendship Hall in Khartoum to celebrate the peace deal. "The agreement is in place and we will remain committed. and will implement (it)", he said.
"The agreement we have just signed today must map the end of conflict and war in our country", Kiir said after signing the deal.
"These outstanding issues that are not yet resolved we shall resolve them as soon as I land in Khartoum", said Kiir who added that the agreement when finalized will hold due to fact it was not mediated under pressure and intimidation.
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Most notably, the deal would see rebel leader Machar reclaim the office of vice-president, which he lost after Kiir accused him of plotting a coup in 2013.
Concerning the boundaries and the number of states of South Sudan, it is agreed that an Independent Boundaries Commission will be established to address the issue.
The power-sharing deal stipulates that there will be 35 ministers in the bloated transitional government, including 20 Kiir allies and nine backers of Machar along with representatives of other rebel factions. The transitional Parliament will comprise 550 lawmakers, 332 from Kiir's side and 128 from Machar's faction.
A similar arrangement, however, fell apart in July 2016 when fighting erupted in the capital, Juba, and Machar fled the country.
"My government and I know the conflict in South Sudan has resulted in a financial and political burden", Kiir said.
About 2 million South Sudanese have become refugees in neighbouring countries.