Sony Ericsson Mobile Communications AB (Sony Ericsson) is a joint venture established in 2001 by the Japanese consumer electronics company Sony Corporation and the Swedish telecommunications company Ericsson to make mobile phones. Both companies have ceased making their own mobile phones, letting the new company use Sony's knowledge in consumer electronics and Ericsson's know-how in cellular technology.

The company's global management is based in London; it has Research & Development in Sweden, Japan, China, the United States, and the United Kingdom; and approximately 5,000 employees in total worldwide. The current President is Miles Flint, and the Corporate Executive Vice President is Ericsson veteran Jan Wäreby.

Sony Ericsson announced its first joint products in March 2002 and now has a full product portfolio covering all target groups. Sony Ericsson mobile phones are known for having good quality displays, stylish design, an attractive user interface, good imaging capabilities, and a large set of entertainment features. Sony Ericsson introduced new Walkman-branded W series music phones in 2005 (five models to date, W550i, W600i, W800i, W810i and W900i).

In 2004, Sony Ericsson sold about 42.3 million mobile phone units. In 2003, shipments were 27.2 million phones.

Sony Ericsson posted its first profit in the second half of 2003, buoyed in part by sales of its new line of camera phones and a strong showing in Asia. To that date Sony Ericsson had steadily lost money since it was founded in 2001. In full fiscal year 2004 Sony Ericsson earned the net income of 315 million euros and sales of 6.5 billion euros.

According to the IT research consultants Gartner, in the first quarter of 2006 Sony Ericsson was the fourth largest mobile phone manufacturer, behind Samsung, Motorola, and Nokia, and held market share of around seven percent.