Riverbank will close from the junction with the A259 Brighton Road to Lower Beach Road from Monday, January 15, according to West Sussex County Council.
A spokesman said: “The closure of this public footpath is needed to maintain safety while construction work on the Adur Tidal Walls flood defence scheme is carried out.”
The closure will remain in force for six months, after which time it is expected an extension will be necessary.
During the closure, access to properties accessed from Riverbank, including houseboats, will be maintained at all times, added the spokesman.
An alternative route for the general public will be available via The Saltings and Beach Green and indicated with signage on site.
When complete, the Environment Agency’s flood defence scheme will significantly reduce flood risk to over 2,300 properties in Shoreham and Lancing.