The launch of the smart phone, the Sony Xperia S, effectively removes Ericsson, which first started making telephones in 1878, from the consumer electronics market.
The name change is a result of Sony's decision to buy Ericsson's half of the partnership in October, 2011 for €1.05 billion ($1.47 billion).
The separation is expected to be formally completed by the end of January.
The Japanese-Swedish groups joined forces in October 2001, and were among the top telephone companies worldwide in the mid-2000s.
Despite considerable rises and falls financially, the Sony-Ericsson venture became the sixth biggest player in the global market before the two firms went separate ways.
Sony bought Ericsson's share of the company in 2011 with the goal of switching the focus heavily to smartphones.
Ericsson CEO Hans Vestberg said at the time that the separation was a ‘logical step,' and that the decade long venture together had been a ‘perfect match'.
The Xperia S has a 4.3 inch screen and features a 12 megapixel camera, a 1.3 megapixel video calling camera on the front, and a 1.5 GHz dual-core processor.
The phone will be available to buy at the end of the first quarter this year.