Dermot McDermott, who established East London-based Kilnbridge, has transferred his entire holding to the trust, representing 800 Kilnbridge staff.
It now ranks as one of the largest employee-owned construction contractors in the country.
McDermott will remain as chief executive of the business and with the support of the existing senior leadership team will continue to drive the business forward.
Last year the firm raised revenue 15% to £91m and almost trebled pre-profit to £5.7m after a shift in emphasis towards larger, more complex infrastructure projects.
He said: “As an employee-owned business, Kilnbridge will continue to thrive and deliver for our clients in line with our deeply-held values of responsibility, integrity, collaboration and excellence.”
This included work for Crossrail and the complex concrete heads structures for the cooling system at Hinkley Point nuclear power station. Cash held improved from around £5m to over £18m in the year to June 2020.
Founded in 1992 as a small building and civil engineering company, Kilnbridge has since grown into a specialist engineering and construction firm delivering complex engineering projects across the country.
Kilnbridge now works across infrastructure, rail, energy, defence, aviation, commercial property and residential sectors.
In addition to its London HQ, the firm now also has offices in Birmingham and Belfast as well as a manufacturing facility in Northampton.