Media tablet sales will double this year globally to 12 crore units from 6 crore units in 2011.
Apple's iOS will dominate media tablet operating system (OS), with a projected market share of 61.4 per cent of worldwide in 2012.
"Despite the arrival of Microsoft-based devices to this market, and the expected international rollout of the Kindle Fire, Apple will continue to be the market leader through the forecast period," Gartner said in a report.