The project was authorised by the Mersey Tunnel (Liverpool/Wallasey) etc. Act 1965. Edmund Nuttall Limited began work in 1966. Construction took five years to complete. The approach to the tunnel on the Wirral side uses the former railway cutting that carried the Seacombe branch line. It was officially opened by Queen Elizabeth II on 24 June 1971.
Kingsway comprises identical twin tubes. Each has two 3.7 m (12 ft) wide lanes. They carry on average 45,000 vehicles a day (almost 16.4million per year). A single car journey through the tunnel currently costs £1.70 (2017). Manned and automatic tollbooths are located on the Wallasey side. Of the two tunnels crossing the River Mersey, Kingsway is the only tunnel able to take HGVs.
Over 75 miles of wiring was installed in the tunnel as part of a 2016 upgrade to the lighting. The upgrade saw the tunnel fitted with LED lights which were more energy efficient and longer lasting than the lights they replaced.