Years of intense campaigning and days of last-ditch lobbying will finally come to an end when 22 members of FIFA's executive committee hold a secret ballot to choose the hosts for the two tournaments.
England, Russia, Spain/Portugal and Netherlands/Belgium were to make one last formal presentation for their 2018 bids before FIFA delegates begin voting behind closed doors at 2:00pm local time (1300 GMT).
Rounds of voting will continue until one bid receives an absolute majority of ballots. Final results are expected to be announced at around 4:00pm (1500 GMT) at Zurich's Messezentrum conference hall.
The vote will bring the curtain down on the most controversial World Cup votes in years, with FIFA facing myriad allegations of corruption which led to two executive committee members being suspended.
FIFA president Sepp Blatter has acknowledged that the decision to stage votes for two tournaments at the same time was a mistake, making illegal horse-trading between bids inevitable.
The 2018 race has seen England, Russia and Spain-Portugal vying for supremacy in an increasingly acrimonious bidding war. The Dutch-Belgian campaign is regarded as an outsider.
Russian Prime Minister Vladimir Putin raised the stakes on Wednesday when he issued a thinly veiled attack on the English bid, saying media reports alleging FIFA corruption were part of an orchestrated "smear campaign."
England 2018 officials, who have distanced themselves from reports critical of FIFA, did not respond to Putin's comments.
Privately however, England officials believe Putin's decision not to travel to Switzerland suggests that the Russian bid, seen as the clear favourite earlier this week, may be vulnerable.
British bookmakers William Hill installed England as joint favourites late Wednesday after Putin's announcement that he would not be in Zurich.
However an outbreak of crowd trouble at an English League Cup match between Birmingham and Aston Villa late Wednesday threatened to tarnish England's bid.
Five people were arrested and fourteen injured, including four police officers in the trouble, as the spectre of hooliganism reared its head.
Both the English and Spain-Portugal bids have sent heavyweight delegations in a show of support for their respective campaigns.
British Prime Minister David Cameron, heir to the throne Prince William and football icon David Beckham are pushing the English bid.
The Iberian bid will be boosted by the presence of Spanish Prime Minister Jose Luis Rodriguez Zapatero and Portuguese counterpart Jose Socrates.
Holland and Belgium launched Thursday's final presentations by promising to host the greenest World Cup ever, touting plans to make two million bicycles available to fans attending the tournament.
Russia, Spain-Portugal and England were to make presentations later Thursday.
On Wednesday, the bidders for the 2022 tournament - Australia, the United States, Qatar, South Korea and Japan - laid out their final pitches.
The favourites are the United States, Australia and Qatar, with Japan and South Korea seen as rank outsiders.
But the chances of Asia getting the World Cup in 2022 were dealt a potential blow when China's top football official said his nation should bid for the 2026 edition, according to state press on Thursday.