Sony sank to a 138 billion yen (£801 million) quarterly loss because of expenses related to exiting the personal computer business.
The Tokyo-based maker of the PlayStation 4 game machine, Bravia TV and Walkman digital player also reported a loss of 128.4 billion yen (£745 million) for the fiscal year to March.
It had recorded a 41.5 billion yen (£241 million) profit the previous fiscal year. For January-March last year, Sony reported a 93 billion yen (£540 million) profit.
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Earlier this month, Sony acknowledged it would end up with more red ink for the fiscal year than it had earlier forecast because of costs related to its Vaio PC operations and a drop in the value of its overseas disc manufacturing business.
Sony forecast a 50 billion yen (£290,000) loss for the year ending next March.
The firm has lost much of the cachet that stemmed from once being at the cutting edge of consumer electronics. In recent years it has fallen behind in digital recorders and flat-panel TVs while also facing competition from a host of new players that can make appliances at lower costs.
In gadgetry, it is US rival Apple and Samsung of South Korea that have dazzled with their innovations.
In February, Sony announced it would withdraw from the PC business, despite the popularity of the Vaio brand among some Sony fans, especially in Japan.
The deal to sell Vaio to a Japanese conglomerate was signed earlier this month and the transaction is set to be completed in July.
Sony's red ink is flowing despite an improvement in sales, which rose 14% to 7.7 trillion yen (£44 billion) for the fiscal year.
It is also struggling despite the perk that Japanese exporters such as Sony get from a favourable exchange rate, which boosts the value of overseas earnings.
Sony said it trimmed losses at its TV operations, which have been struggling for nearly a decade, a big problem for a company that built its reputation on the image quality of its TVs.
It is splitting off its money-losing TV division to run it as a wholly owned subsidiary.