"Following the resignation … we have taken the opportunity to reflect on the overall performance of the province, including its strengths and challenges," Mokonyane told reporters in Johannesburg.
"In order to consolidate our position, I have decided to bolster the executive council by assigning new and existing members to various portfolios."
Mokonyane said provincial health minister Ntombi Mekgwe would take over from Mmemezi.
Mmemezi quit after an integrity commission report presented to the Gauteng legislature found him guilty of contravening the province's code of conduct and ethics.
The report referred to Mmemezi using a government credit card and covering up an accident in a government vehicle. Mmemezi resigned from his position last Wednesday.
The document was adopted unanimously by the legislature, though the opposition Democratic Alliance made a declaration that other allegations against Mmemezi regarding his time with the Mogale City municipality and his time as provincial minister should be investigated.
Although Mmemezi resigned from his position he would still stay on as a member of the provincial legislature. Mokonyane said this was not her decision.
"I am the premier, I appoint [provincial ministers] … I don't deploy ANC members to the legislature," she said.
Mokonyane said she would not be taking any further action against Mmemezi as the matter had moved beyond the executive council and it was now in the hands of the ANC's integrity commission.
Despite his indiscretion, Mokonyane said Mmemezi had done well in terms of his mandate as local government and housing minister.
"He was one of those visible ministers working with the community … he tried to close the gap between the community and government."
Two new ministers, Hope Papo and Nkosiphendule Kolisile, were sworn in on Monday.
Papo would take over as health minister from Mekgwe. Mokonyane said Papo had been part of the Gauteng legislature for 14 years and had spent some time in the health department.
Economic development minister Qedani Mahlangu would head the province's infrastructure development portfolio.
Kolisile would take over as economic development head. He was a former chair of the economic development cluster in the legislature and has been part of the economic development portfolio committee, Mokonyane said.
"I'm of the firm view that this team will enable us to carry out the mandate that we have been given by the people of Gauteng," said Mokonyane.
Outgoing infrastructure development minister Bheki Nkosi was appointed the new head of the Gauteng gambling board.
"Let me take this opportunity to thank the outgoing [minister] Bheki Nkosi for his contribution," she said.
Mokonyane said she would announce the appointment of the new director general of the Gauteng provincial government on Tuesday. – Sapa