"The transitional government of national unity gives its consent for the deployment of the regional force", the government and the security council said in a joint statement, which was read out by Martin Elia Lomoro, the South Sudanese cabinet affairs minister.
It's hoped the 4,000 troops of the Security Council-mandated Regional Protection Force will provide the stability to allow some people displaced by the 3 year conflict to return home.
Lamek, who spent three days in South Sudan prior to arriving in Ethiopia, said the protection force is necessary because the situation in South Sudan is "more alarming that we imagined".
UNMISS has faced considerable criticism over its failure to protect civilians during the July violence, which included the rape of civilians sheltered just outside its camps.
The UN had threatened an arms embargo if the peacekeepers were rejected.
Since July the government has resisted a United Nations proposal to send 4000 East African troops to South Sudan to reinforce the struggling peacekeeping mission.
South Sudan's government has accepted the deployment of a 4,000-strong regional protection force recently mandated by the United Nations Security Council, in addition to the roughly 12,000 UN peacekeepers already serving in the African nation.
President Kiir had opposed the deployment of additional troops, initially touted as an "intervention force", as breaching national sovereignty.
Power said that the United Nations operation had "an impartial mandate" to protect all civilians.
The communique further states that the Transitional Government has expressed its readiness to implement chapter 5 of the agreement on the resolution of the conflict in South Sudan, and would work with African Union in setting up the hybrid court for South Sudan.
Power added that the next step following the high-level commitments achieved during the talks was to work out how to see them through. "The number one obstacle for (the peacekeepers) fulfilling their mandate to this point has been the severe restrictions on their movements".
Fighting that erupted in the capital, Juba, in July killed hundreds and sparked fears of a renewed civil war.
The Council, as well as various senior UN officials, including UN Secretary-General Ban Ki-moon, repeatedly spoke out against the violence, calling for calm and the safety of civilians. He is now in Khartoum and has been replaced by Taban Deng Gai.
Both government and rebel forces have been accused of widespread abuses in the recent fighting and during the civil war that began in December 2013 between supporters of Kiir and Machar.