On Wednesday, 139 of the 168-member Chamber of Deputies voted for the amendment, which was proposed by Interior Minister Milan Chovanec of the Czech Social Democratic Party (ČSSD), in response to an EU directive on firearms that was adopted earlier this year.
"We do not want to disarm our own people at a time when the security situation is deteriorating," Chovanec said during the parliamentary debate on Wednesday.
"Show me a single terrorist attack in Europe perpetrated using a legally-owned weapon," he said.
'Interior Minister Milan Chovanec for the defense of his home and country.'
The new law states that Czech citizens have the right to acquire, keep and bear arms in order to ensure the security of the state.
It means that the approximately 360,000 licensed gun-owners in the Czech Republic are allowed to carry their weapons in public and use them in case of a public order emergency, such as terrorism.
The EU directive, which was drawn up by the Commission in the aftermath of terrorist attacks in Paris and Brussels, was adopted by the EU Council in April. It includes a ban on civilian use of short semi-automatic firearms with loading devices over 20 rounds and long semi-automatic firearms with loading devices over 10 rounds, as well as long firearms that can be easily concealed, for example by means of a folding or telescopic stock.
As well as the constitutional amendment, which still has to be approved by the Senate and the President, the Czech government has also said it will file a complaint with the European Court of Justice about the directive by August 17.
Although Western European countries such as France, Belgium, Germany and the UK have suffered several terrorist attacks in recent years, the Czech Republic has not seen any attacks. The Global Peace Index 2016 ranked the country the sixth safest in the world.