The exchange, the sixth busiest in the world according to Coinmarketcap.com, said it has stored "all of clients assets in safe cold wallet", which operates on platforms not directly connected to the internet.
Bithumb plans to compensate users affected by the hack - they intend to cover all the losses.
The Bithumb theft highlights the security risks and the weak regulation of global cryptocurrency markets.
The recent hack is Bithumb's second attack this year and the third attack on a South Korean cryptocurrency exchange.
"Local exchanges have quite poor security systems in place", said Kim Seung-joo, a professor at Seoul's Korea University.
South Korea's spy agency later accused North Korea of being responsible after the stolen information was used to carry out scams.More news: Isco stands out with 8/10 performance as Spain struggle to beat Iran
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The exchange has not responded to CoinDesk's request for comment.
Mun Chong-hyun, chief analyst at ESTsecurity, said digital coins would continue to be juicy targets for hackers around the world.
Deposit and withdrawal services were halted "for the time being", the exchange said.
Over the past 14 months, the total amount of damages by hacking attacks on cryptocurrency exchanges stood at some 97.7 billion won, and few customers have received due compensation, according to the authorities. In December 2017, Slovenian cryptocurrency marketplace NiceHash was hit by a cyber-attack which led to losses of $64m.
On June 11, another South Korean cryptocurrencyexchange Coinrail said it was hacked.
South Korea emerged previous year as one of the world's major markets for trading in bitcoin and other virtual currencies. As reported by Bitcoin Magazine earlier this month, South Korean Conrail lost around $40 million to hackers where lesser known tokens such as PundiX were stolen.