The company's co-chief executive officer unveiled the Gear at the annual IFA consumer electronics show in Berlin, Germany Wednesday.
The smartwatch acts as an extension to a smartphone by discreetly alerting users to incoming calls, messages and emails on its screen, which measures 1.63 inches diagonally. The Gear must be linked with a smartphone to perform its full range of functions. The pairing is done wirelessly over a Bluetooth connection built in to both sides.
"With Gear you're able to make calls and receive calls, without ever taking your phone out of your pocket," Pranav Mistry, a member of Samsung's design team, told reporters at the launch.
Mistry demonstrated the calling function on the Gear by holding it up to his ear and talking into a microphone hidden in the watch. The watch then relays the call to a smartphone linked to it wirelessly over a built-in Bluetooth connection.
The Gear uses Google's Android operating system, just like many of the phones and tablets made by Samsung. The strap, which comes in six different colors, holds a basic camera that can be used to shoot photos and video.
The Gear will be compatible initially with two Samsung products also unveiled Wednesday - the Galaxy Note III, which is a smartphone with a giant 5.7-inch screen and a digital pen, and the Galaxy Tab 10.1, a tablet computer with a 10.1-inch screen comparable to Apple's full-sized iPad. But Samsung promised to update other Galaxy phones and tablets to work with the Gear in future.
The number of apps that work with the Gear is still limited. More than 70 are currently supported, including Facebook, Twitter and RunKeeper. That compares with the hundreds of thousands available for leading smartphones.
Unlike normal watches that can happily tick away for years on end, Samsung only promises a full day's use out of the Gear before it has to be charged.
The Gear goes on sale in the United States and Japan next month. The rest of the world will get their hands on it sooner, on Sept. 25, with prices starting at $299. That is about twice the price of currently available devices such as the Sony SmartWatch and the Pebble, which was funded through more than $10 million pledged by individuals on fundraising website Kickstarter.
The Associated Press contributed to this report.