The gain from about 2 million a year ago represents the fastest growth in Rhapsody's 13-year history. The Seattle-based company cited competitors like Apple and Spotify for helping raise awareness of the category. Spotify, the global leader, said in June it had doubled its paying user base from a year ago to 20 million. Apple launched its streaming music plan last month.
The growth in streaming music services globally comes as download sales from stores such as iTunes is slowing.
Rhapsody cited high growth in markets where piracy had been rampant including Italy, Colombia and Brazil.
Rhapsody is also launching a redesign of its app beginning this week.
The option to save songs for offline listening will be featured prominently, in part to address the misunderstanding that the streaming app always requires an Internet connection. Offline listening has grown 40 per cent in the past six months.
Ethan Rudin, Rhapsody's chief financial officer, says many consumers are unaware that offline listening is even an option and end up buying music despite also paying for a $10-a-month subscription and thereby having access to millions of tracks. A new downward arrow beside each track makes that option apparent.
"People have started to figure out streaming is great when you're on a subway, when you're on an airplane," he said. "We are bringing that feature to the forefront as part of the redesign."