By clicking the 'I'm a Voter' button (or megaphone), users broadcast their status as a voter to their friends' network without disclosing to whom their vote was cast.
"We estimate conservatively that nearly 400 million people around the world will see the megaphone this year. This includes India, where over 31 million people saw the megaphone," the world's largest social networking site said in an emailed response.
Facebook has about 1.28 billion monthly active users with 81.2 per cent of its daily active users outside of the US and Canada.
The 'I'm a Voter' button, which was made available in the 2008 and 2012 presidential elections as well as the 2010 midterm elections in the US, will appear for voters in next week's European Parliament and Colombian elections.
In June, it will be rolled out in Korea in June and Indonesia in July, while users in Sweden, Scotland and New Zealand will see it in September, Facebook said.
Apart from these, the other countries in which "Facebook plans to roll out the 'I'm a Voter' megaphone this year include Brazil (October 5) and the US (November 4), it added.
According to a study by The Nature, an additional 340,000 citizens voted after seeing that their friends had clicked the button to indicate they had cast a ballot in the 2010 midterm elections in the US.
In India too, there was a lot of buzz on Facebook around elections, which saw the world's largest democracy choosing its new Prime Minister Narendra Modi.
The website, which has over 100 million users in India, was flooded with pictures posted by voters with election ink painted on the index finger as the various phases rolled on.
Facebook estimates that 29 million people in India made 227 million interactions through posts, comments, shares, and likes about the elections from the day they were announced till May 12.