The junction, known as the Black Cat roundabout, is a busy intersection where the A470 meets the A55.
The work will include widening the junction, the construction of safer crossings for pedestrians and cyclists, the installation of traffic signals at key locations and an upgrade from the current street lighting to an energy-efficient LED alternative.
The routes for cyclists and pedestrians will also link with the current path on the A470 to encourage active travel in the area.
Traffic signals will help manage congestion on the off slips, reducing the length of queues and the traffic speed to improve safety on the roundabout.
The work would originally have been carried out after the summer embargo. But traffic levels on the A55 are almost half their normal level as a result of the coronavirus pandemic, providing a window to complete the work earlier than intended with minimal disruption to the public.
Construction workers will follow strict social distancing at all times.
Transport and North Wales Minister Ken Skates said:
“This is an important scheme on a very busy junction where two of our major roads meet. The scheme will encourage walking and cycling by making the junction safer. Traffic speeds will also be lowered as a result of the improvements, helping reduce the number of accidents.
“This is the first of our pinch point schemes to go ahead and it will deliver a real difference to all forms of transport once completed.
The first phase of works is scheduled to begin on 17 June and will continue until the end of September, depending on weather conditions, but every effort will be made to finish ahead of schedule if possible.
If the coronavirus restrictions are eased and traffic increases, the contractors will modify their way of working to ensure disruption is kept to a minimum. Works which are likely to cause more disruption have been prioritised to take place during the first phase while traffic levels remain lower than usual.
The works will require the narrowing of the lane on the junction 19 circulatory and there will be a single lane closure on the A55 eastbound and westbound off slip in addition to the installation of discrete areas of traffic management as the project progresses to accommodate some installation works. Work will be carried out during extended daytime shifts.