Russian President Vladimir Putin announced that Kadyrov died in a blast that killed 14 during celebrations of the Soviet Union's 1945 victory over Nazi Germany.
He has been a target of the Chechen resistance for years, but especially so since winning a widely discredited presidential poll last October.
The election completed a remarkable turnaround for the former mufti and rebel leader who once called on Chechens to fight a jihad against the Russians.
But Kadyrov later abandoned his comrades-in-arms to become head of Chechnya's brutal pro-Kremlin administration.
This earned him the undying hatred of Chechen resistance fighters, and made his presidency farcical given his obvious lack of support among the people.
Born in 1954 in Central Asia, Kadyrov studied Islam in Uzbekistan in the 1980s, and rose to prominence as head of the first Islamic institute in the North Caucasus.
He was appointed deputy mufti in Chechnya in 1993, when Dzhokhar Dudayev's separatist regime was barely tolerated by Moscow.
And by the time he took over as mufti in 1995, he was combining religious activities with being a guerrilla commander in the first Chechen war.
Aslan Maskhadov has called for
Kadyrov to be killed
It was during the country's period of de facto independence from 1996-1999 that Kadyrov turned against his colleagues.
He accused them of adopting an "extremist" version of Islam, and of mismanaging the country.
Controversially, he openly condemned Chechen resistance fighter Shamil Basayev for attempting to forge an Islamic state in neighbouring Dagestan.
"[Russia] gave us everything that is Chechnya, [saying]: 'Do with it what you will' - but we did not use it properly," he said when asked why he changed sides.
Moreover, when Russian forces returned to the republic in 1999, Kadyrov called on Chechens to desist from armed resistance.
Separatist leader Aslan Maskhadov immediately branded him "enemy number one", and called for him to be killed.
Kadyrov has since been the target of numerous assassination attempts. A woman came within metres of killing him in May 2003, when she blew up herself and 14 bystanders at a religious festival.
Although in the eyes of the Chechen rebel leadership he remained the Kremlin's puppet, Kadyrov has sometimes been critical of Russia's actions.
He has complained of Russia's failure to invest adequately in Chechnya's future, and accused Moscow's forces of brutality against Chechen civilians.
However, in the run-up to last October's elections his own human rights record came under the spotlight.
Chechens said he commanded a private army that frightened residents and became a new source of terror, carrying out killings, kidnappings and torture.
"[Russia] gave us everything that is Chechnya, [saying]
'Do with it what you
will' - but we did not
use it properly"
And the fact that he had Russia's backing made him widely feared in the republic.
Putin did not publicly endorse Kadyrov before the elections, but took him on a trip to the United Nations the previous month and regularly appeared with him on nationwide television.
Observers thus saw the Kremlin's hand behind all other major candidates pulling out of the elections or being disqualified, leaving Kadyrov in effectively a one-horse race.
So it was no surprise when Kadyrov was said to have won the election with more than four-fifths of the vote, with most of the ballots counted.
Kadyrov's election, in the view of many analysts, was stage-managed by Moscow as part of an exit strategy from an unending, unwinnable war.
After four years of slaughter, critics said, the Russians were trying to do what people once urged the US to do in Vietnam - declare victory and leave.
For Vladimir Putin, ensuring Kadyrov's victory was an essential step towards convincing the weary Russian public the Chechen millstone had been lifted from their necks.
But Sunday's assassination attempt proves that Russia's Chechen nightmare is far from over.