Fendalton-Waimairi councillor Raf Manji has today also been named as chair of the council's finance committee.
Ms Buck says she is looking forward to her new role.
"This is not a ceremonial role," she said.
"My role will be to ensure that when our residents come to the council with suggestions and ideas, where possible, they happen."
Mr Manji, a first time councillor who had a career in the finance industry including 11 years as an investment banker in London, says he is looking forward to making a contribution in an area that he knows well.
"My priority will be to get the council finances onto a stable footing, understanding the financial commitments and responsibilities of the Long Term Plan as well as working on risk management strategies to ensure that there is confidence about the council's long term finances."
Councillors are working to establish the new standing committees and will make announcements on chairs and deputy chairs, along with portfolio responsibilities as soon as that work is complete.