Elections Ontario said there will be 88 polling stations around the city, the same number as the last general election in June.
The polls are open from 9 a.m. to 9 p.m.
Elections Ontario said voters who received a voter card should go to the polling location that is indicated on the card, or they may be redirected.
This is different from the recent municipal election in Greater Sudbury, where people could vote anywhere in the city.
People who did not receive a voter card in the mail can register and vote at any polling station, but will require a piece of identification with a name and address, and an official document such as a bank statement or utility bill.
Elections Ontario is encouraging people who did not receive a voter card to find the polling station closest to them by using the address search function on the agency's website. All polling locations are accessible, they added.
Race involves allegatons
The race has been dominated by criminal allegations against the Liberals and "turncoat" criticism aimed at their candidate.
Glenn Thibeault left the federal NDP to run for the provincial Liberals in the byelection, prompting federal NDP Leader Tom Mulcair to call him untrustworthy and a turncoat.
The Liberals appointed Thibeault instead of holding a nomination contest, and their previous candidate in the June general election alleges the party offered him a job or appointment in exchange for stepping aside.
The provincial police and Elections Ontario are investigating Andrew Olivier's claims following complaints from the opposition parties.
Olivier is running as an Independent, but polls suggest it's a race between Thibeault and NDP candidate Suzanne Shawbonquit.
Olivier also released audio of his conversations with two Liberals, which he said back up his claims, but added he just wanted to focus on the issues in the campaign.
The Liberals have denied the bribery allegations, saying they were trying to keep Olivier involved in the party after Thibeault's appointment was already decided.
The byelection was triggered when New Democrat Joe Cimino resigned after just five months on the job.
The Liberals had previously held the seat for 19 years, so with the former stronghold in play again, Premier Kathleen Wynne has showered attention on the riding. She has made several visits to Sudbury since calling the byelection.
And it seems voters are more engaged this time around, with advance polls showing a higher turnout than advance polls in the general election.