Mr Williamson said the revelation, contained in secret files held by Czech security services, proved that the Labour leader 'cannot be trusted'.
The Defence Secretary's intervention has provoked a furious response from Mr Corbyn's office, which angrily labelled the claims as a 'false' and 'ridiculous' smear.
Confidential papers show the hard-left Labour leader met the Czech agent at least three times after being vetted by communist handlers in 1986.
Two of the meetings are said to have taken place in the House of Commons.
Records of one meeting showed an espionage agent noted how Mr Corbyn – who was given the codename 'COB' – was 'occasionally explosive'.
Speaking at a Nato meeting in Brussels, South Staffordshire MP Mr Williamson said: "Time and time again he has sided with those who want to destroy everything that is great about this country, whether it is sympathising with terrorists, backing rogue regimes, or cosying up to those who want to inflict pain and misery on the British people.
"That he met foreign spies is a betrayal of this country. He cannot be trusted."
In response, a spokesman for Mr Corbyn said: "Gavin Williamson should focus on his job and not give credence to entirely false and ridiculous smears, which as we know from Darren Osborne [jailed for the Finsbury Park Mosque attack], can have a potentially deadly effect.
"Jeremy has consistently made the correct calls in the interests of security and peace, including on the Libyan intervention and his opposition to the disastrous Iraq war that has caused catastrophe in the region and made us less safe at home."
The secret records summarised Mr Corbyn's political outlook in 1986, describing him as: "Negative towards USA, as well as the current politics of the Conservative Government."
The documents also suggest he was 'positive' towards the Soviet bloc and was 'supporting the Soviet peace initiative'.