These are the headline findings in the "Smartphone forecasts and assumptions, 2007-2020" study by GSMA Intelligence, the research division of GSMA, the global association of mobile operators.
It predicted that smartphone connections will grow threefold from its current level of two billion, and will make up two-thirds of the nine billion mobile connections in place by 2020.
Much of this growth will be driven by demand in the developing world, which already accounts for two-thirds of all smartphones and is forecast to account for four-fifths of all global smartphone connections by that date.
Asia-Pacific currently accounts for about half of worldwide smartphone connections, but the market still has plenty of room to grow.
Smartphone adoption in the region currently stands at below 40%, the report said, compared to many developed markets where smartphone penetration is approaching the "ceiling" of up to 80%, at which point growth tends to slow.
China, at 629.2m, tops the report's global list of smartphone connections, followed by the US (196.8m), Brazil (141.8m), India (111m), Indonesia (95m), Russia (83.9m) and Japan (66.1m).
Despite having much smaller populations compared with these countries, the UK and France still have 45.4m and 43.5m respectively, while Germany has 48.5m.
The top five countries with the highest smartphone adoption rates (as a percentage of total connections) are Qatar, the UAE, Finland, South Korea and Norway.
And Sub-Saharan Africa, currently with the lowest smartphone adoption rate of 15%, is expected to become the fastest-growing region over the next six years as affordable devices become more available and mobile broadband networks extend their reach.
Hyunmi Yang, chief strategy officer at GSMA, expected smartphones to be the driving force of mobile industry growth over the next six years and said "lifestyle" brands stand to gain as the industry evolves.
"In the hands of consumers, these devices are improving living standards and changing lives, especially in developing markets, while contributing to growing economies by stimulating entrepreneurship," she said.
"As the industry evolves, smartphones are becoming lifestyle hubs that are creating opportunities for mobile industry players in vertical markets such as financial services, healthcare, home automation and transport."
Data sourced from GSMA; additional content by Warc staff