It means the Xperia Z5 Premium can both capture video in “ultra-high definition” quality and then play it back on its 5.5in (14cm) display without downgrading the footage.
All the firm’s Z5 handsets also feature a new camera module the first time the part has been completely overhauled since 2013’s original Z1 handset.
Sony’s mobile division loses money, but its camera components are profitable.
Apple, Samsung, Xiaomi and Huawei are among rival handset makers to have used earlier generations of the Japanese company’s photo capture technologies.
However, Sony said the 23 megapixel sensor involved was being kept as an “exclusive” to its own devices for the time being. it forecast its image sensor wing which also makes parts for bigger cameras would generate 580bn yen ($4.8bn; £3.1bn) of sales over the same period.
The company acknowledged that there was still a limited amount of professional content available in 4K which provides about four times the number of pixels as 1080p high definition video.
But it said the Z5 Premium would upscale videos streamed from YouTube and Netflix to take advantage of the display.
One of the big concerns about high definition screens is that they run down batteries more quickly.
Sony says its use of a “high capacity” 3,430 mAh battery and memory on display tech which allows a static image to remain on show without requiring extra processing power should mean the handset lasts for “up to two days” between charges.
Sony’s new camera module benefits from the introduction of a “closed-loop actuator” stabilisation system.
This adds a position sensor to the part, which is used to detect small disturbances and then compensate for them by making the lens move up and down in its housing in a related fashion.
As a result, it should be able to film less jerky video clips.
The addition of a sixth camera element causes more light to fall on to the sensor, which should aid low-light photography.
Sony has also added more “phase-detection” pixels to the sensor. These are used to speed up auto focus and now cover the complete frame rather than just its central area.
The result is that the sensor can react more quickly to action occurring on the edge of shot.