The sentence was comprised of 100 years for murder by starvation and 100 years by direct homicide, Justice Diana Kavedza said, reading out the judgement.
Prosecutors said Mackenzie, who led an apocalyptic Christian church in a forest near eastern Kenya's Indian Ocean coast, had told his followers to starve themselves to death, along with their children, to reach heaven before the end of the world.
His accomplices threatened and beat victims to ensure they followed his orders. The emaciated bodies were found scattered in shallow graves and dumped in latrines. Some had been buried alive.
Mackenzie, wearing a grey polo shirt and black trousers, smiled as he entered a tent set up outside the court where the hearing was held.
He had denied murder charges, saying he did not force the victims to starve. The court rejected his defence.
The case shocked Kenya in April 2023 when police began uncovering bodies in Shakahola Forest near the coastal town of Malindi.
Although only the cases of 190 children and one adult victim were covered by the trial, the Kenya National Commission on Human Rights says 448 bodies were ultimately found in the forest.
Mackenzie is also accused of ordering the deaths of 52 people found at a separate location in a village 30km away, bringing the suspected total toll to 500. He has pleaded not guilty in that case.
The scale of the killing is comparable to that of a doomsday cult that killed more than 700 people in Uganda in 2000, and the 1978 Jonestown massacre in Guyana when an American cult leader killed more than 900 people by ordering them to drink poison.
Stephen Mwiti, 48, father of six of Mackenzie's child victims and husband of one of his convicted accomplices, said his wife had taken the children to Shakahola where they were starved to death.
Even if the adults had agreed to fast, "what about the children?" Mwiti told Reuters ahead of the sentencing.
"I lost children and I will not be able to get them back no matter what happens to Mackenzie and his accomplices," Mwiti said.
"I expect him to be sentenced to death or be jailed for life so that he never comes out to cause more deaths."
Dan Mackenzie, one of Mackenzie's sons, said his father did not spare his own family.
"I didn't end up in Shakahola, because I didn't believe anymore about ... going to heaven. So I left the church and started doing my own thing," he told Reuters.
"I lost friends too, and my younger brother. It's justice to the people who we lost over there in Shakahola."
Mackenzie had been on the radar of the authorities since 2017 when his premises were searched by police. In 2019, authorities shut down Mackenzie's church in Malindi and he relocated to the nearby Shakahola Forest.
The discoveries prompted calls for tighter oversight of religious groups. President William Ruto appointed a task force in May 2023 to review the legal and regulatory framework, and separate government-backed and Senate proposals were published in 2024, though they have yet to be passed into law.
In 2023, Ruto said he took responsibility as president for the government having failed to prevent the deaths.
