The South Korean giant's mobile chief DJ Koh told a New York event the Galaxy S8 and S8+ handsets marked "a new era of smartphone design."
The two handsets, fitted with screens of 5.8 and 6.2 inches, include Samsung's upgraded digital assistant Bixby, competing in a crowded field that includes Apple's Siri, Google Assistant and Amazon Alexa.
Koh said Bixby would provide users with "more and more personalized help," using voice commands to navigate apps and services.
Their release comes after Samsung was forced to recall its Note 7 phones for catching fire due to overheating batteries.
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The debacle cost the South Korean company billions of dollars in lost profit and hammered its global reputation and credibility, during a torrid period when it has also been embroiled in a corruption scandal.
The company apologised to consumers for the recall and was forced to postpone the S8 launch. Its investigation blamed the problems on faulty batteries.
Samsung later embarked on a campaign to restore its battered reputation, placing full-page advertisements in US newspapers, admitting it "fell short" on its promises.