Supervising director of traffic, Inspector Brian Surimalefo, said the newly completed two-lane Mataniko Bridge into Chinatown and the road around the City Council Roundabout, both built with funding and support from the Japan International Cooperation Agency, will be closed from 10am to 5pm on Wednesday.
He said the opening event would take four hours.
Inspector Surimalefo said he hoped that with the public's co-operation the ceremony would go smoothly with no unnecessary delays or traffic incidents.
After flooding in Honiara in 2014 the bridge into Chinatown was damaged beyond repair and New Zealand installed a temporary Bailey bridge which has now been replaced with the permanent two lane crossing.
Further down river the main Mataniko bridge has also been replaced by a new four-lane bridge.