The audience erupted with cheers as Cook proclaimed that he had "one more thing." It was how Jobs used to close his keynote addresses.
That one more thing was named the Apple Watch, rather than the iWatch that many people had been speculating.
Cook says Apple had to invent a new interface for the watch xiaomi hongmi because simply shrinking a phone would not work. Much of the interaction will be through the dial on the watch, which Apple calls the digital crown. It's used to zoom in and out of a map, for instance.
Apple also worked with app developers to create new functionality. Users will be able to unlock room doors at Starwood hotels or remind themselves where they parked cars with a BMW app.
The new watch will come in a variety of styles and straps, with a choice of two sizes. Watches from competing vendors have been criticized for being too big for smaller wrists.
The watch will require one of the new iPhones or an iPhone 5, 5s or 5c. It will be available early next year at a starting price of $349.
Though much of the attention has been on new gadgets, the software powering those gadgets is getting its annual refresh. Apple considers iOS 8 to be its biggest update since the introduction of the app store in 2008.
Among other things, iOS 8 will let devices work better in sync. For instance, it will be possible to start a message on an iPhone and finish it on an iPad. With an upcoming Mac upgrade called Yosemite, it will be possible to continue working on that same message on a Mac computer as well.
Closing out the event, U2 performed on stage before Cook made its new album, "Songs of Innocence" available for free to all customers of Apple's iTunes.
Apple's stock was up 1 percent to $99.36 in Tuesday's late afternoon trading.
The Apple Watch, the company's first completely new product in four years and its first wearable device, is also Apple's most ambitious expansion since CEO Tim Cook replaced Steve Jobs three years ago.
The watch made its debut alongside a service that seeks to turn Apple mobile devices into a payment system that will eliminate the need for consumers to bring cash or plastic cards to the checkout stand.
Apple Inc. also used the occasion to present the next generation of its iPhone - two larger models that reflect the company's attempt to catch up with rivals that have been winning over fans with bigger screens that enhance videos and game playing.
The bigger iPhones are expected to unleash pent-up demand among Apple zealots who have been pining for a larger screen, virtually assuring the new models will be a hot commodity this fall and through the crucial holiday shopping season.
Although the iPhone figures to be Apple's main moneymaker for the foreseeable future, the new smartwatch was the marquee attraction of Tuesday's show.
The Cupertino company held Tuesday's coming-out party in the same Silicon Valley auditorium where Jobs unveiled the Macintosh computer 30 years ago.
Just as the Mac convinced more people to buy PCs for the first time xiaomi mi2 , Apple is convinced that its new watch will become a must-have accessory for the masses after it goes on sale early next year.
