The South Korean electronics giant released two versions of the device: a 5.9-inch S9 and 6.2-inch S9+. Both feature an almost bezeless display that was introduced on the S8 last year.
Samsung said pre-orders for the devices began Sunday with general sale on March 16.
Key features include:
Samsung focused it's unveiling on the bolstered camera. It has a feature that lets users take clear pictures in very low light by taking 12 photos at once and stitching them together to form a crisp image.
Another key camera feature is super slow motion video.
Samsung also launched a feature called AR Emoji, which allows a user to take a selfie and turn it into their own custom emoji. The camera can track a person's face and mimic their facial expression on the digital version of themselves too.
AR Emoji rivals Apple's iPhone X feature called Animoji. These are animated characters that mimic a person's face when they move it. Samsung's offering is different because it allows a person to create an emoji version of themselves.
The phone itself does not look radically different to the Galaxy S8, but analysts said that might not be a problem because Samsung is trying to attract users on older phones. Globally, the most common Samsung flagship models in use are the S7 and S7 Edge, which were released in 2016 with a combined market share of 5.26 percent, according to IHS. The Galaxy S6 from 2015, and the four-year-old Galaxy S5 are the next most popular.
This gives Samsung a large install base of users to target with the new S9, which compared to these older devices is a big upgrade.
"It's different to a handset two or three years ago. The kind of devices that consumers have in their hand is ready for an upgrade," Ian Fogg, head of mobile at IHS, told CNBC by phone ahead of the launch.
In 2017, Samsung saw smartphone shipments rise nearly 2 percent while the entire market was relatively flat, according to IDC. Users are holding onto their phones for longer while rising prices of high-end devices could be putting consumers off.
And the electronics titan saw rising competition last year in the high-end smartphone space from Apple and Chinese vendor Huawei.
To counter this, Samsung revealed a new trade-in program in partnership with mobile networks, where users can get money for their old devices. The hope is that it will make buying an expensive phone more palatable and encourage people to upgrade, which will be key for growth in an increasingly saturated smartphone market.
"At the end of the day, if Samsung really wants to keep a user base properly, they need to give the tools for current users to trade in devices to make sure they feel like they aren't losing money," Francisco Jeronimo, research director for European mobile devices at IDC, told CNBC by phone ahead of the launch event.
Samsung also showed an improved version of Bixby, its smart digital assistant. In one demonstration, Samsung showed how Bixby could live translate a piece of text. The South Korean electronic giant also unveiled a new version of Dex, which allows a user to connect their smartphone to a bigger screen, to turn it into a full PC experience.
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