"2018 is is an incredibly important year for elections. Not just in the US mid-terms, but, around the world, there are important elections -- in India, Brazil, Mexico, Pakistan and Hungary -- and we want to make sure we do everything we can to protect the integrity of these elections," the Facebook founder and CEO said.
The Facebook chief has been under mounting preassure over the hijacking of its user data by Cambridge Analytica, a British political consultant firm.
Cambridge Analytica is reported to have been involved in "all kind of projects" in India and had major political parties like Congress as it clients. Christopher Wylie, a former Cambridge Analytica employee, had told a British parliamentary committee that the British firm even has an office in India.
In his first formal congressional appearance, the Facebook chief sought to quell the storm over privacy and security lapses at the social media giant that have angered lawmakers and the network's two billion users.
"It was my mistake, and I'm sorry," Mark Zuckerberg said. "I started Facebook, I run it, and I'm responsible for what happens here."
"It's clear now that we didn't do enough to prevent these tools from being used for harm," he said. "That goes for fake news, foreign interference in elections, and hate speech, as well as developers and data privacy."
"There are people in Russia whose job it is to try to exploit our systems and other internet systems and other systems as well," he said.
"So this is an arms race. They're going to keep getting better and we need to invest in getting better at this too."
Mark Zuckerberg has previously acknowledged the social network failed to do enough to prevent the spread of disinformation during the last US presidential race.
He also revealed that Facebook is cooperating with the US special prosecutor investigating Russian interference in the 2016 vote.
The social media giant has taken out full-page apology ads in several major US and UK newspapers, including the New York Times, Wall Street Journal and The Washington Post.
(with inputs from agencies)