The airport's Terminal 2 opened amid fanfare on Wednesday, with the Airport Authority saying things were going smoothly.
The authority expects 4,200 travellers to use the terminal on its first day of operations.
T2 allows travellers to check in, clear immigration and undergo security checks, before proceeding to Terminal One for departure.
"Our passengers [were] very happy and we have some 'wow effects' in the terminal, I think they they were [like] 'wow'," the authority's chief executive, Vivian Cheung, told reporters.
"We have a lot of LED, animation, and new designs emphasising technology, and we have our in-house design for self-check in system, which only requires 45 seconds to go through the entire process.
"We want to help the airlines to migrate to a full-automation process, which will actually help passengers have better experiences and also reduce the labour needs."
Cheung noted the first flight using T2 was operated by Hong Kong Airlines and left for Shanghai Pudong International Airport at around 8am.
Six other carriers, including AirAsia, are set to begin using T2 from Thursday.
By June 10th, the number of airlines is expected to go up to 15, with HK Express the last to relocate.
T2 was closed in 2019 for reconfiguration as part of the three-runway project before its reopening.
It's expected to handle around eight million passenger trips in its first full year of operations before rising to some 30 million per year.
Its dedicated departure concourse and boarding gates are scheduled to open at the end of next year.
Edited by Edmond Fong
