The changes include reducing traffic speeds to 30 km/h throughout the CBD and making the city more pedestrian-friendly by improving footpaths.
Lichfield Street, at present a one-way route, will be made two-way while Tuam Street will become a one-way road.
Christchurch City Council will consult affected businesses and residents from early June.
The four projects will cost $72 million including a $27 million contribution from the council.
They will be completed in time for the opening of the new bus interchange in May next year.