The screens of the Galaxy S8 and bigger S8+ are also larger despite the devices being about the same size as last year's S7 and S7 Edge.
This time, both models feature displays that curve round the phones' sides.
The launch follows Samsung's botched release of the Note 7, which was recalled twice after fires.
The South Korean firm blamed the problem on battery faults and said it had since put in additional safety measures, including X-ray scans of batteries.
The company has also become mired in a corruption scandal in its home country.