The ministers from Mozambique, Swaziland and Zambia, support staff from the Sadc secretariat and representatives of Thabo Mbeki, a Sadc mediator and former South African president, were due to meet separately with Mugabe and Tsvangirai.
They were also to meet Arthur Mutambara, leader of a small faction of the MDC in the unity government.
It was not immediately clear how Thursday's negotiations progressed, but analysts said there were slim chances of a breakthrough as Mugabe's Zanu-PF and the MDC remain at loggerheads over some aspects of their power-sharing pact.
The MDC says Zanu-PF has blocked the swearing-in of some of its officials.
Ayesha Kajee, director of international human rights exchange at Witwatersrand University in South Africa, said that the ministerial delegation is "not going to have much effect".
Speaking to Al Jazeera on Friday, she said there were reports that Joseph Kabila, the chair of Sadc and president of the Democratic Republic of Congo (DRC), was heading to Zimbabwe to try to break the impasse.
"Seeing that one of the ministers is actually from a country [Swaziland] that doesn't have a very good democratic record of its own, has led analysts to predict that this won't have much effect on the impasse in the government of national unity," Kajee said.
Under the coalition agreement, the foreign ministry is controlled by Zanu-PF, in power for nearly three decades and is accused of human rights abuses.
The home affairs portfolio, which oversees immigration as well as police, is shared by the MDC and Zanu-PF after the longtime rivals were unable to agree on which would control the key ministry.
The Sadc delegation arrived in Harare hours after Manfred Nowak, a UN rapporteur on torture, called on Thursday for action against Zimbabwe after his deportation.
Zimbabwean officials denied him entry and forced him to board a South Africa-bound plane on Thursday after he was detained by security officials on arrival overnight.
Nowak said he had been invited to Zimbabwe by Tsvangirai.
"I think it sheds light on the present power structure of the unity government if the prime minister invites me for a personal meeting and his office is not in a position to clear my entrance to the country," said Nowak.
"That is a very alarming signal about the power structure of the present government."
He said he would recommend that the UN Human Rights Council (UNHRC) take action against Zimbabwe, but added that immediate moves were unlikely.