John O'Conner has secured a 10-year £15m grounds maintenance and arboriculture contract with St Albans City & District Council.
The contract started on 1 March and there is an option to extended for a further five years, worth another £7.5m.
Under the deal, the firm will also provide services for nearby Harpenden Town Council from 1 April and Sandridge Parish Council from 1 March, subject to final service-level agreements. All three councils worked on the procurement process.
John O'Conner, based in Welwyn, Hertfordshire, will provide grounds maintenance for parks, green spaces, cemeteries, closed churchyards, land surrounding council buildings and local authority leisure facilities.
It will also operate the Assisted Garden Maintenance Scheme for tenants who have mobility difficulties and take on duties previously operated by the council - tree surveying, countryside rangers and the Green Flag programme.
This is the third contract the company has won with St Albans, with which it has worked since 2000, although the addition of the two extra councils will be new. This contract is at least twice as long as previous agreements.
Managing director Matt O'Conner said: "It's fantastic for us. When we have a long-term contract it gives us a chance to invest in the service completely. We're investing in equipment, machinery and staff, and we can put in long-term training plans."
The company is spending around £750,000 on equipment, plant and vehicles and is, along with council officers, seeing what the market has to offer. A modern fuel-efficient fleet is expected to save on operating costs.
O'Conner said the council was looking for "a long-term partner they were building long-term partnership with".
He added: "The council wanted to get the most competitive quotes and the balance between long-term relationships and the most economically advantageous tender. Chopping and changing contracts too often was detrimental. We've got a number of long-term contracts - it does work."
Joint working Councils aim to save money
Combining three councils' ground maintenance needs into one contract will save money for the local authorities.
"The councils have not all come together before. It makes sense," said John O'Conner managing director Matt O'Conner. "The councils are doing a lot of work to get the specifications in line but there's a lot of communality already and it's good for the taxpayer.
"Together we all need to look at ways of delivering services for less. The councils want high-quality grounds maintenance but they are looking at the hours and frequency of visits."
He said his company saves money by retaining staff. "We get more bang for our buck when we spend on training." There will be no job losses as a result of the contract, O'Conner added.