Around 100 acres of land between Falkirk and Grangemouth will be transformed into parkland and a new canal hub as part of the £41m scheme.
It will also feature two 30-metre high, stainless steel horses' heads called the Kelpies, which have been designed by sculptor Andy Scott.
Under the terms of its contract, RJ McLeod will build a lagoon for water sports, more than five kilometres of paths, family play areas, an outdoor events area and a cafe.
Alongside that, the Glasgow company will be tasked with creating new wild flower meadows and improving the wetland and woodland areas to protect the biodiversity of the site.
A small number of staff are on site already and the contract will run until next summer.
It is understood more than 80 jobs will be supported by the deal, while RJ McLeod is also taking on 12 trainees during the construction phase.
Jamie Corser, business development manager of RJ McLeod, said: "We are very pleased to be awarded this contract, not just because we are able to play our part in delivering this exciting project, but because it also assists in us being able to provide sustained employment for our staff and operatives, many of whom are from the central belt."
Mike King, programme director of the Helix Trust, said: "The central park is the beating heart of the project and this latest contract award will help establish key connections between the various elements of the Helix.
"The award also signifies another significant step forward in creating what will be one of the most exciting and unique community and visitor experiences in the UK.
"RJ McLeod's track record for delivering large scale projects made them a sound choice to take this ambitious programme forward."
A partnership between Falkirk Council, Scotland's Canals and Central Scotland Forest Trust was awarded £25m by the Big Lottery Fund's Living Landmarks programme for the project.
Additional funding for the central park development came from Avondale Environmental, through the Landfill Communities Fund.
John Holt, director of Avondale Holdings, said: "The Helix will undoubtedly make a positive difference to the environment and to the lives of local people."
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