It was found that the council was "performing well" in the governance, leadership and strategy, and financial decision-making and transparency categories.
The council was judged "better than competent" in the areas of service delivery and asset management, and communicating and engaging with the public and business.
Mr Dalton added the evaluation "makes a mockery of some of the criticism's aimed at my council".
There has been scrutiny directed at the council recently, most notably over their proposed multi-use sports facility, concern over the redevelopment of the Napier Conference Centre, and on the status of the city's drinking water.
However, the mayor said the assessment had confirmed was "actually, you guys are going a good job for the city".
The assessment also indicated that the council were now working cohesively as a team - last year the council underwent a $1million restructure which saw 78 roles disestablished to make way for 78 new ones.
However, he said there was always room to improve and they would be working to achieve the highest mark - participating councils are assessed by independent experts every three years and given an overall rating from triple AAA to C.
The assessment noted the council was "doing many things well" - highlighting its "ambitious goals", sound financial position, and generally well-delivered operational services.
It noted the council was nearing the end of a "significant period of transition, which has seen amalgamation rejected and the organisation restructured to better align with the goals set in its Long Term Plan.
"It is in a strong financial position which, coupled with a motivated and capable workforce, leaves it well-placed to carry out its proposed additional investment in the future of its city."
Improvements noted included public accountability for all major projects, a greater focus on risk management and reporting, and ensuring management aligned each project delivery programme with its LTP to ensure objectives were attained.
The assessment was carried out over several days in February, and engaged elected members, staff, and involved a significant amount of research by the independent assessors, council chief executive Wayne Jack said.
He said the rating confirmed their own understanding of where improvement was needed.
"NCC is committed to lifting and demonstrating our performance so that the community we serve can have greater confidence in what we do and how we do it," he said.