"We were taken by the vision for the Boulevard Gardens project in Kuirau Park and so we're very pleased to be able to make a contribution that will help enhance such an iconic facility," he said.
Councillor Karen Hunt said Firth's sponsorship was a generous contribution to an innovative local community project.
"We're very grateful to Firth for their support and foresight.
"The company's generosity, and their commitment to the Rotorua community and our Rotorua 2030 goals, represents another significant public-private partnership helping inject new vitality into our city."
The second pour of concrete was completed last week, meaning two-thirds of the boulevard's length has now been completed. The new paving is integrated with the Green Corridor pathway through Kuirau Park.
Boulevard surfacing is expected to be finished by the end of July, weather permitting, with themed gardens being installed in the next 18 months.
They are to be connected by a combined public walkway and cycle path integrated with the new Green Corridor, and linking key attractions and activities within the unique geothermal reserve. A further link to the Rotorua Aquatic Centre is planned for the future.