The teenager carried a triceps injury into the final having pulled out a high-scoring final dive in the semis simply to qualify for the Sunday showdown.
He began brightly, placing third after four rounds, but a disappointing penultimate dive saw him drop to sixth.
The 2009 world champion’s signature three-and-a-half-forward-somersault dive on the last did not come off, and he could not claw his way back into medal contention.
"I found out yesterday after a scan that I've torn my tricep again," Daley, who missed last month's European Championships because of an elbow injury, said.
"I've been diving with a numb arm which is a bit of a weird sensation. I can't straighten my arm properly which makes entry to the water really difficult.
"This year has just been one thing after another. But I really wanted to compete. I would've competed even if my arm was falling off."
Qui Bo recovered from a shaky start to secure a second straight gold in the event as dominant China ended the diving competition with nine titles out of the 10 contested.
Lying equal fifth after a fluffed first attempt at the spectacular hilltop Montjuic pool, Qui produced a pair of stunning efforts on the third and fourth of his six dives to amass a whopping 581.00 points, comfortably beating Olympic champion David Boudia of United States into second on 517.40.
Boudia, who pipped Qui for gold in London last year, finished with silver for the second World Championships in a row and Germany's Sascha Klein took bronze with 508.55 in a repeat of the top three places at the previous championships in Shanghai in 2011.
China won all 10 golds in Shanghai but were denied another sweep in Barcelona after the German pair of Klein and Patrick Hausding won the 10-metre synchronised platform.
China's Cao Yuan and Zhang Yanquan, the Olympic champions, finished third behind the Russians.
"The best thing is that I won two medals at the world championships this year, I'm so happy I just can't believe it," Klein said.
American teenager Katie Ledecky stormed to gold in the 400 metres freestyle, becoming only the second woman after Italy's Federica Pellegrini to break four minutes.
The 16-year-old Ledecky, gold medallist at 800 metres at last year's London Olympics, was on course to break Pellegrini's world record of 3:59.15 but slipped off the pace in the final 100 metres to finish in a still-blistering time of 3:59.82.
Spain's Melanie Costa Schmid lifted the home support inside the hilltop Palau Sant Jordi by taking silver in 4:02.47.
Jazmin Carlin came within a whisker of securing Britain's first medal on the first night, but the 22-year-old agonisingly missed out on bronze after being pipped into third by just 14 hundredths of a second by New Zealand's Lauren Boyle.
The Brit’s time of 4:04.03 was a new personal best, a good omen according to Carlin ahead of her outings over 1500m and 800m later in the week.
"I am absolutely gutted. I really wanted to be on that podium. I fought hard and it's disappointing to be so close to bronze but that's what happens," she said.
"I've got the rest of the week to get myself up. If someone would have told me last year I would finish fourth at the World Championships I would have taken it.
"On the day you want to be on the podium, you want to be the best but the 400, is probably the weakest of the three, which is what my coach says, but I'm excited for the 1500m and the 800m."
Olympic champion Camille Muffat of France finished a disappointing seventh.
China's Sun Yang ticked the first box on the way to a possible treble of freestyle golds when he comfortably won the 400 metres.
The 22-year-old, who was Olympic champion in London last year, led from the start to improve on his silver medal from Shanghai two years ago with a time of three minutes 41.59 seconds.
Kosuke Hagino of Japan took silver, more than three seconds behind in 3:44.82 and American Connor Jaeger won the bronze in 3:44:85.
Sun, who also won the 1,500m gold in London, is bidding to join Australia's Grant Hackett as the only men to win World Championship freestyle titles at 400m, 800m and 1,500m.
Megan Romano swam a blistering final leg to overhaul Australia's Alicia Coutts and snatch gold for United States in the 4x100 metres relay.
Romano put up a split time of 52.60 seconds, with only Cate Campbell going quicker with 52.33 leading off for Australia, as the Americans improved on their silver behind Netherlands at the previous championships in Shanghai two years ago.
Australia, Olympic champions in London last year, led until the final 50 metres through Campbell, her sister Bronte and Emma McKeon but Romano was too good for Coutts and touched in three minutes and 32.31 seconds.
The Australians finished in 3:32.43 and Netherlands, who pipped the U.S. to silver in London, were third in 3:35.77 ahead of Sweden.
Jeremy Stravius produced a scintillating final leg as France stormed from behind to see off the United States, Russia and Australia and steal 4x100 relay gold.
Olympic champions in London last year, the French were fourth when Stravius dived into the water but he hauled in American James Feigen, Russia's Danila Izotov and James Roberts of Australia to touch in three minutes 11.18 seconds.
The United States matched their silver from London in a time of 3:11.42 and Russia pipped Australia to the bronze in 3:11.44.
Fabien Gilot's contribution on the third leg was also significant as he was the only man to go under 47 seconds, recording a split time of 46.9 compared to Stravius's 47.59.
Britain’s women fell to water polo Olympic semi-finalists Hungary in the knockout match at the Worlds.
The Brits ultimately lost 14-5 (4-2, 4-2, 2-1, 4-1) at the conclusion of the game which was a much closer-fought affair than the scoreline suggested.
- Sports & Recreation
- United States
- David Boudia