Age UK has sold its Personal Alarms business and its parent company, Aid-Call, to Axa's PPP healthcare arm for an undisclosed sum.
More than 50,000 elderly people use the personal care alarms, which are worn as a wristband or around the neck, and aid those who wish continue living at home.
Users can press a button on the device which alerts an emergency call centre if they fall while at home or become ill.
The alarms are available at a starting price of £69 and Age UK charges a weekly fee of £3.47 to keep them connected.
"This transaction brings together Age UK's understanding of older people and Axa PPP healthcare's expertise," Age UK said today in a statement.
Aid-Call made £1.7m in operating profit in the year to 31 March 2015, according to the company's most recently filed accounts at Companies House, while turnover reached £8.67m.