"We propose that the triathlon event (swimming, cycling and running) take place around this spectacular location, at the foot of the Eiffel Tower, in the Seine," Hidalgo told a senate committee.
"And to do that we will have to go further in cleaning up the water," added Hidalgo, who has repeatedly insisted swimming in the Seine will be possible by 2024.
The Paris mayor is in the process of pedestrianising the main road alongside the Seine and is pushing a raft of projects refocusing city life around what she believes is an under-used asset.
"It would need to be a project to make it possible (to swim in the Seine) permanently and not only for the Games," she told the committee.
Paris, along with Rome, Budapest and Los Angeles, is bidding to host the 2024 Olympic Games.
The winning candidate will be announced in September 2017.
Rome's bid was dealt a potentially fatal blow on Wednesday after the city's mayor said she would not give her formal backing.