Mr Orban, who won a fourth consecutive term in elections on April 3, has used the special legal order in the past, once due to migration and later during the Covid-19 pandemic.
In announcing the new “state of danger” on Tuesday, Mr Orban said the war in Ukraine represents “a constant threat to Hungary” which was “putting our physical security at risk and threatening the energy and financial security of our economy and families”.
He said a "war state of danger" would take effect to allow the government "to respond immediately and protect Hungary and Hungarian families by any means possible".
The move came after Mr Orban's ruling party passed a constitutional amendment to allow for states of emergency to be declared when wars or humanitarian disasters were taking place in neighbouring countries.
Watch: Hungary denies reports it was warned about Russia's invasion of Ukraine
It gives Mr Orban’s government sweeping powers to enact laws by decree without parliamentary oversight, and permits the temporary suspension of and deviation from existing laws.
It had implemented similar measures in response to the Covid pandemic to outcry from critics and legal observers, who argued it eroded democratic norms.
That special legal order was set to expire on June 1.
The governing Fidesz party won a fourth-straight election victory on April 3, giving Mr Orban, the longest-serving leader in the European Union, an additional four-year term.