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In an error-strewn display, the 2012 bronze medallist needed 102 points from his closing dive to reach the final.
However, he managed only 50.40 to finish in last place with 403.25 - well short of the personal best of 571.85 he set in Friday's preliminary round.
"It's really hard to accept. I've worked so hard," said Daley, 22.
"Yesterday I scored the highest score ever in an Olympic Games. Today it wasn't meant to be. That's what diving does sometimes.
"I truly am heartbroken because I feel like I am in the peak physical condition and I could have won."
British Diving performance director Alexei Evangulov had said Daley was "in the best shape and best form of his career" before the Olympics.
Daley, who won a bronze medal in the 10m synchronised platform with Dan Goodfellow, suggested he would compete again in Tokyo in 2020.
"I'm so happy with how GB have done, so proud to be part of it and I wanted to be able to stand on top of that podium, so it will be another four years' hard work," he said.
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China's Chen Aisen, 20, claimed his second gold of the Games by winning the final, which took place later on Saturday.
Chen, who also won the 10m synchro alongside Lin Yue, scored 585.30 points to finish ahead of Mexico's German Sanchez (532.70) and defending champion David Boudia of the United States (525.25).
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Polish national Daria Pionko, 21, was found in Springwell Road, Holbeck, at about 01:30 GMT on Wednesday.
Police said Miss Pionko, who had been living in Leeds, was a sex worker. She was taken to hospital for treatment, but died a short time later.
A 38-year-old man was arrested in connection with the incident.
Miss Pionko had been found unconscious with injuries consistent with an assault, West Yorkshire Police said.
Officers found her in a defined managed area where sex workers operate during set hours, the force said.
The force appealed for witnesses to come forward and in particular anyone who was in the Springwell Road area between 20:00 Tuesday and about 01:30 Wednesday.

3 November 2014 Last updated at 08:42 GMT
Air safety investigators say the device, designed to slow down the craft, activated at the wrong time without a command from the pilots.
But they say it's too soon to determine the exact cause of the crash and it may take as long as a year to carry out the investigation.
Virgin Galactic's SpaceShip Two, crashed during a test run over the desert in California.
One pilot was killed and another is recovering in hospital.
Virgin Galactic had aimed to send tourists into space early next year, and has already taken more than 700 flight bookings costing more than Â£156,000 each.
Britain's Tom Daley said he was "heartbroken" after a shock semi-final elimination in the Olympic 10m platform diving competition.
[NEXT_CONCEPT]
A woman who died after being found seriously injured in Leeds, sparking a murder inquiry, has been named by police.
[NEXT_CONCEPT]
An investigation into what caused a spacecraft to crash, has said that a safety device activating at the wrong time, could have been the reason.