Council officials said they would install the signs along the Passage West and Rochestown greenway in an effort to cut down on accidents involving cyclists, pedestrians, and dog walkers.
Parts of the greenway will also be widened from 3m to 4m in an effort to provide more space so cyclists and pedestrians will not come into contact.
However, as it is an old railway line, it would be impossible to widen it to four metres in all areas as there were land space limitations.
They made the comments after Fianna Fáil councillor Seamus McGrath raised the issue at a meeting of the Ballincollig/Carrigaline municipal district council.
Mr McGrath said the latest victim was a woman who had to receive hospital treatment after being knocked down by a cyclist a week ago.
He said he is very worried that somebody is going to get seriously injured or worse if those using the greenway are not educated with a code of conduct.
Council officials said they had reached agreement with the city council, which controls part of the greenway, to install the same type of warning signage.
Sinn Féin councillor Michael ‘Frick’ Murphy described the present situation as “an accident waiting to happen” and maintained a lot of cyclists were “flying”.
“Safety needs to be addressed as a matter of priority, especially in terms of protecting the elderly and people with disabilities who are using it.”
Fine Gael councillor John Collins said the threat of a serious accident was always there and it needed to be impressed on walkers to stop using earphones because they can not hear anything coming up behind them.
Fianna Fáil councillor Daithí Ó Donnabháin said he had walked the greenway himself and had seen cyclists travelling way too fast.
Cllr McGrath also suggested that some of these warnings should also be painted onto the greenway surface at different intervals.