The research group says that there will be 45.6 billion app store downloads in 2012, with free apps accounting for 89% of these (40.1 billion).
Paid-for downloads will total 5 billion.
"In terms of the apps that consumers are buying, 90% of the paid-for downloads cost less than $3 each," said Gartner research director Sandy Shen.
Similar to free apps, lower-priced apps will drive the majority of downloads. Apps between 99 cents and $2.99 will account for 87.5% of paid-for downloads in 2012, and 96% by 2016.
As to be expected, Gartner finds that Apple's App Store continues to dominate, with app downloads to increase 74% year-on-year to reach 21 billion in 2012. And while the firm expects most app downloads to be dominated by the respective app stores from Apple, Google and Microsoft, it does also foresee Amazon and Facebook have an increasing influence.
"Amazon has appealed to users with its strong brand, global presence and a good selection of high-quality content while Facebook's recently launched App Center, supporting both mobile devices and desktops, will become a powerful competitor due to its strong brand and leading position in social networking and gaming," said Ms. Shen.