Scottish Borders Council said the promenade at Eyemouth will be blocked to the public when coastal flood alerts are issued.
Last year two teenage girls were swept from the harbour wall at Eyemouth by a 20ft swell. One of the girls, Katie MacLean, was in a coma for a week.
After a study into "overtopping" along the structure, the promenade will be closed when flood warnings are made by the harbour master or by the Scottish Environmental Protection Agency (SEPA).
Police and council officials will enforce the temporary barriers, and warning signs will also be erected.
The risk was uncovered after an earlier structural and maintenance study recommended a subsequent overtopping assessment. The cost to implement its recommendations is £11,000.
Gordon Edgar, of the council's roads and infrastructure committee, said: "Once the council was made aware of the risk to pedestrians we organised a plan of action and consultation with the local community and emergency responders to inform how the seawall promenade could be made safe during a wave overtopping event.
"We have now noted the findings of the Eyemouth Seawall Wave Overtopping and Flood Study and are taking actions with respect to pedestrian safety.
"As an immediate action, we will ensure that temporary barriers are deployed by local neighbourhood services staff to close off the seawall promenade to the public in the event of a coastal flood warning being issued by SEPA or the harbour master, to ensure people are protected."
The council is looking at the regeneration of Eyemouth, the coastal and river flood risk. The future of the seawall is a key focus.
Eyemouth is one of 28 locations in Scotland to be involved in a SEPA coastal flood warning project.