Wainwright joins from Laing O’Rourke where he was a director and group board member responsible for Finance.
He will sit on the Byrne Group board and will take overall responsibility for the corporate finance and treasury activities of the company.
The appointment comes as Byrne Group eyes a projected increase in turnover to nearly £400m.
Wainwright said: “I am looking forward to working for one of the country’s most respected specialist construction businesses and assisting its continued development.
“This is an exciting time for construction and there are many new future opportunities.”