Three-term councillor Ryan Hamilton will take on a new role as senior chair, providing support to the mayor. Hamilton will also chair the Strategic Growth and District Plan Committee.
Southgate said growth, infrastructure and planning were the most important and challenging issues facing the city over the coming triennium and that she, O'Leary and Hamilton were a "strong and experienced trio".
"These issues are coming at us in the face of unprecedented change in the sector with major reforms to work through. The pace of change will be relentless and we need strong and experienced leaders in key positions," Southgate said.
"A three-pronged approach will provide that, and I am grateful to have two resilient and experienced people in support, chairing critical committees on behalf of our city."
O'Leary and Hamilton will also be charged with providing support to other chairs since the council now comprises 15 elected members instead of 13 in the last triennium because of the establishment of the two new Māori ward seats.
According to the final results, the two new Māori Ward councillors are Moko Tauariki and Melaina Huaki, confirming the preliminary results.
All previous ward councillors who stood again have been re-elected and are joined by six new faces around the table.
Hamilton's first council meeting will be on November 17, where Southgate will formally propose six main committees.
Previous deputy mayor Geoff Taylor appears to have been sidelined by Southgate in the new committee structure announced so far, scoring only a deputy chair position on the Economic Development committee; although there are still some other appointments to be announced, including regional representation roles.
Those announced so far are:
An Infrastructure and Transport committee, chaired by O'Leary with Maxine van Oosten as deputy chair; a Strategic Growth and District Plan committee, chaired by councillor Hamilton with Sarah Thomson as deputy chair; and a Community and Environment committee chaired by Kesh Naidoo-Rauf and Anna Casey-Cox as deputy chair.
Southgate will also propose a Finance and Monitoring committee, chaired by van Oosten and Moko Tauariki as deputy chair; an Economic Development committee, with Ewan Wilson as chair and Geoff Taylor as deputy chair; and a Regulatory and Hearings committee, with Mark Donovan as chair and Ewan Wilson as deputy chair.
Additionally, three sub-committees will be proposed: Community Grants Allocation, Dog Control Panel and Traffic, Speed Limit and Road Closure Hearings Panel. A Strategic Risk and Assurance Committee will continue to be chaired independently.
There are still a number of other appointments to work through, including regional representation responsibilities, which will be announced over the coming weeks.
With all votes counted, Hamilton's vote count is 29.4 per cent.
Meanwhile, Waikato District confirms veteran councillor Jacqui Church as mayor. Church is the first female to be elected to this position in the Waikato district and says she is honoured to continue to pave the way for women in local governance.
"I am passionate about leading this council and, having represented the Tuakau-Pōkeno Ward for the last nine years, have robust experience in the governance space and always act with the best interests of our entire district at heart," Church said.
Church has appointed Western Districts General Ward councillor Carolyn Eyre as her deputy mayor.
Eyre said she finds Church's passion enthusiasm and commitment for the district and its residents inspirational.
"As a ward councillor for a large rural ward, I believe the appointment indicates mayor Jacqui's intent to honour her commitment to strengthening the connection with our rural communities," Eyre said.
Church and Southgate are two of four new female leaders in the region joining newly elected Matamata-Piako mayor Adrienne Wilcock and Waipā mayor Susan O'Regan.
Final results have also come in for Waikato Regional Council, showing no changes to the preliminary results.
The elected members will be sworn in at the first official council meeting on October 27. A decision on who will be the chair and deputy chair will be made by councillors at that same meeting.
Below is a list of all Hamilton councillors.
Mayor Paula Southgate
East Ward Ryan Hamilton Anna Casey-Cox Maxine van Oosten Mark Donovan Kesh Naidoo-Rauf Andrew Bydder