The dramatic announcement came moments after it became clear that more than half of the rebel region's population had fled the advancing Azerbaijani forces.
It drew the curtain on one of the world's longest and seemingly most irreconcilable "frozen conflicts" -- one that successive administrations in Washington and leaders across Europe had failed to resolve in ceaseless rounds of talks.
But it also raised the levels of anger in Yerevan.
Armenian Prime Minister Nikol Pashinyan accused Azerbaijan of conducting "ethnic cleansing" and called on the international community to act.
Baku's 24-hour blitz ended with a September 20 truce in which the rebels pledged to disarm and enter "reintegration" talks.
Two rounds of talks were held as Azerbaijani forces worked with Russian peacekeepers to collect separatist weapons and enter towns that had remained outside Baku's control since the Caucasus neighbours first fought over the region in the 1990s.
Azerbaijani troops have now approached the edge of Stepanakert -- an emptying rebel stronghold where separatist leader Samvel Shakhramanyan issued his decree.
"Dissolve all state institutions and organisations under their departmental subordination by January 1, 2024, and the Republic of Nagorno-Karabakh (Artsakh) ceases to exist," the decree said.
The republic and its separatist dream have been effectively vanishing since Azerbaijan unlocked the only road leading to Armenia on Sunday.
Armenia said more than 70,000 of the region's 120,000-strong population had piled their belonging on top of their cars and left by Thursday afternoon.
Pashinyan said he expected the entire region to clear out "in the coming days".
"This is an act of ethnic cleansing of which we were warning the international community about for a long time," he told a cabinet meeting.
Azerbaijan's foreign ministry retorted: "Pashinyan knows perfectly well that Armenian residents are leaving Karabakh on their own volition."
Moscow also issued a guarded statement that appeared to absolve Baku of any blame. There was "no direct reason" for people to leave Nagorno-Karabakh, said Kremlin spokesman Dmitry Peskov.
Moscow had "taken notice" of the dissolution decision and was "closely monitoring the situation", he added.
Nagorno-Karabakh has been officially recognised as part of Azerbaijan since the Soviet Union's collapse in 1991.
No country -- not even Armenia -- supported the statelet's independence claim.
'Reduced to dust'
But ethnic Armenian separatists have been running the region since winning a brutal war in the 1990s that claimed tens of thousands of lives.
The fighting was accompanied by allegations of massacres against civilians and gross violations of human rights that many in the region recall to this day.
The latest chapter of the bloody feud between mostly Christian Armenia and predominantly Muslim Azerbaijan dates back to the years in the 1920s when the region was handed to Baku by the Soviets.
Yet its origins stretch back much further.
Armenians are believed to have first settled in the winegrowing region in the 2nd century BC.
It was handed to Azerbaijan by Moscow just years after the massacre of ethnic Armenians by the Ottoman Empire during World War I.
Many ethnic Armenians still derogatively refer to Azerbaijanis as "Turks."
Turkish drones and other weapons transformed Azerbaijan's once-feeble army into a potent fighting force that clawed back large parts of the region in a six-week war in 2020.
Lilit Grigoryan was one of many refugees on the Armenian side of border mourning the loss of her native land.
"It's painful," the 32-year-old said. "We were born and lived (there). Now, everything has been reduced to dust."
Azerbaijan has agreed to allow rebel fighters who lay down their arms to withdraw to Armenia.
But Baku added that it reserved the right to detain and prosecute suspects of "war crimes".
Azerbaijani border guards on Wednesday detained Ruben Vardanyan -- a reported billionaire who headed the Nagorno-Karabakh government from November 2022 until February.
Baku said on Thursday it had charged him with "financing terrorism" and other crimes that could land him behind bars for 14 years.
The United Nations humans rights office urged Baku to afford Vardanyan and other detainees "full respect and protection".
Pashinyan also accused Azerbaijan of making "illegal arrests".
But the embattled Armenian leader's immediate challenge involves navigating an emerging crisis in Yerevan's relations with old ally Moscow.
Pashinyan blamed Moscow for failing to avert Baku's offensive and called Yevevan's current security alliances "ineffective".
He also urged parliament to ratify Armenia's membership of the International Criminal Court (ICC) at a session scheduled for Wednesday.
The ICC has issued an arrest warrant from Russian President Vladimir Putin over his actions in Ukraine.
The Kremlin said Thursday that it would treat Armenia's membership of the ICC as an "extremely hostile" act.