Although preparations were riddled with delays and corruption scandals and May's grand opening was overshadowed by violent protests, over the months the Expo's popularity has increased and crowds have flocked.
The number of visitors soared in recent weeks, leading to five-hour queues to enter the most popular pavilions, including Britain, Italy, Japan and Kazakhstan. Some Saturdays drew up to a quarter of a million people.
The Expo has also played host to figures such as German Chancellor Angela Merkel, Russian President Vladimir Putin and US First Lady Michelle Obama.
Italian PM Matteo Renzi has declared it a "triumphant ride" to success after organizers said they expected the goal of 20 million visitors to be met if not beaten.
For Giuseppe Sala, the Expo's commissioner, the end has come too soon: "I would be the first to want to prolong the Expo but technically its impossible," he said last week.
"The last day is reluctantly confirmed for October 31," said Sala, whose success with Expo has transformed him into a local star now tipped as the favourite for Milan's mayoral elections next year.
Socially just or superficial?
Milan has indeed felt the benefits: the number of tourists leaped 35 percent in September to 910,000, a trend that city hall believes will continue thanks to the increased exposure the Expo has brought to Italy's northern economic powerhouse.
In the short term, the country should see an overall GDP gain of 0.1 percent for 2015 and some six billion euros in tourism revenue.
But there is a risk of serial bankruptcies - between 1,000 and 3,000 companies - in the most 'expo-dependent' sectors such as construction, according to a report by credit insurer Euler Hermes, one of the Expo's sponsors.
Renzi has promised the government will help transform the one million-square-metre (10.7-million-square-feet) venue once its doors close.
Dismantling the pavilions is expected to be completed by mid-2016, to make way for a research and innovation quarter, including the transfer of several scientific faculties from the University of Milan and business hubs.
But beyond the crowd-drawing exhibitions, critics have questioned whether the Expo - held under the slogan "Feeding the planet, Energy for life" - lived up to the lofty goals of promoting sustainable and socially just food systems.
Italian Agriculture Minister Maurizio Martina argued it helped "awaken the interest, commitment and curiosity of millions of people."
Today, he said, they are "more aware of their responsibilities and their duties concerning the important democratic questions about access to food".
But detractors have complained it pandered to the interests of multinational sponsors and countries with a poor record on the environment.
Carlo Petrini, head of the Slow Food movement - which strives to protect local ecosystems and promote clean and fair food -- described it as a "circus" and "a lost opportunity", saying "you cannot boast opulence in a world where people are dying of hunger".
And international Catholic aid agency Caritas criticized the Expo's manifesto as "lacking teeth" and offering "a limited approach to global hunger", with head Michel Roy saying that "the voices of the world's poor are not heard".
The Expo 'torch' now passes to Kazakhstan and the United Arab Emirates, the first of which will organize a smaller-scale international exposition in Astana in 2017, while the latter will host a World Expo in Dubai in 2020.