Run-off elections will be held in 4,827 cities and towns around France where the first round of votes on 15 March was not decisive, with some 16.5 million adults eligible to participate.
Strict sanitation measures will be in place at the polling stations, with masks obligatory for all voters.
The second round was postponed from its initial 22 May date because of the Covid-19 lockdown, with candidates forced to run remote campaigns.
However, Sunday's vote risks seeing another high abstention rate; in the first round abstention was over 50 percent, the highest for this type of election since the founding of France's Fifth Republic in 1958.
Challenge for ruling party
The French president Emmanuel Macron is looking to chart a fresh course for the remaining two years of his term with his La République en Marche (LREM) party.
Efforts to build grassroots support have fallen short, with most of its candidates failing to make it past the first round.
There are 157,632 candidates running in the run-off poll, and major cities such as Lyon and Marseille could see a complete political reshuffle.
Prime Minister Édouard Philippe, whose popularity has soared over his handling of the Covid-19 crisis, faces a close fight to regain his mayor's seat in the northern port city of Le Havre.
A loss by Philippe would almost certainly force Macron into a broad reshuffle of his cabinet.
Close races in major cities
On top of that, several ruling party LREM lawmakers defected in May to form their own parliamentary group, known as Groupe Écologie Démocratie Solidarité (Ecology, Democracy, Solidarity), depriving Macron of an outright majority in the National Assembly (lower house).
Another close race will be run in Paris, where Socialist incumbent Mayor Anne Hidalgo recently sealed an alliance with Greens leader David Belliard, the Europe Écologie-Les Verts candidate (EELV), in her bid for a second term.
Polling stations close at 8pm local time from which point results will start coming in.
Elsewhere,the the overseas French territory of Guiana, the poll has been postponed again due to the rise in the number of cases of Covid-19.
