IDC said it expects tablet sales growth of just 2.1 percent this year, after an increase of 4.4 percent in 2014 and more than 50 percent in 2013.
Tablets appeared to be on a tear two years earlier, but the market is being eroded by use of large-screen smartphones or "phablets" as well as slimmed-down laptop computers.
IDC said it expects "low but positive growth" for the market, with increased focus in the business sector and some gains for Microsoft Windows in the tablet market.
"Despite the growing popularity of phablets, there still remains a portion of the market that wants to use a larger device so they can tailor their experience to the appropriate screen size," said IDC analyst Jitesh Ubrani.
"Meanwhile, an increasing number of vendors behind small tablets are reducing prices and adopting features like voice calling to entice consumers to purchase their products over competing phablets, making the dynamics of phablets vs voice-capable tablets an interesting one to watch."
The Google Android system is expected to retain around 67 percent of the market this year, with its share slipping a bit to 62.9 percent by 2019, IDC said.
Windows meanwhile will likely see its share grow from 5.1 percent in 2014 to 14.1 percent in 2019, according to IDC.
"Microsoft is doing a lot of good things right now and we believe the launch of Windows 10 later this year will not only have a significant impact on Microsoft's share of the market, but on the industry as a whole," said Jean Philippe Bouchard, IDC's head of tablet research.
"There is an appetite for a platform that can provide a productivity experience that remains consistent across multiple form factors and device types, and we believe Microsoft is well positioned to capture some of that demand."