Its 12.7ft (3.9m) diameter has won it a place in the Guinness World Records as the "most slender tower".
The structure, which is due to open this summer, stands 531ft (162m) high.
John Roberts, chief engineer and director of the British Airways i360, said the tower's height-to-width aspect ratio of 41.15-to-one beat those of The Shard and the BT Tower in London.
He said the Shard had an aspect ratio of six-to-one, and the BT Tower had an aspect ratio of eight-to-one.
The tower had used "groundbreaking engineering", he said.
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Architects David Marks and Julia Barfield, who also designed the London Eye, said the i360 built on the design, engineering, technology and innovation behind London's big wheel, taking it to "new heights".
Mr Roberts said the team had not set out to design the project with the aim of achieving a world record; they had just wanted to build a very slender tower.
He said people might think the main challenge was carrying the weight of the 94-tonne pod with 200 passengers on board weighing about 16 tonnes.
But he said: "Amazingly, that's not really the problem of designing the tower. The tower is all about one thing - making it stand up safely in extremely strong winds."
He said Storm Imogen recently brought windspeeds on Brighton beach of about 75mph, but the tower could withstand windspeeds of more than 100mph.
"There's absolutely no way this tower is going to fall over," he said.
The pod, made of 24 segments of handmade glass, will rise up to 137m (450ft) in front of the city's West Pier. It will give visitors views of up to 26 miles along the Sussex coast from Bexhill to Chichester.
Brighton's tallest building - the i360 tower - has now also been declared the thinnest in the world.