Strategy Analytics said Android grabbed 65.8 percent of global tablet sales in the first quarter, up from 53 percent a year ago.
Apple meanwhile saw iPad sales slump and its market share tumbled to 28.4 percent from 40.3 percent a year earlier, the survey showed.
Global tablet sales in the quarter were up 19 percent at 57.6 million units, the market research firm said.
"Android continues to make steady progress and now commands two-thirds of the tablet market share," said Peter King, analyst at Strategy Analytics.
The report said iPad sales were down 16 percent from the same period a year ago.
"We believe that the disappointing performance in the early part of the calendar year is because Apple has changed its product release cycle to the holiday timeframe," King said.
He added that Apple "will likely lose share over the next several months to refreshed Android products, but we believe Apple will win back meaningful high-end market share during the final months of the calendar year."
(Also see: Tablet sales jumped 50 percent in 2013: IDC)
Android sales totaled some 38 million in the period to Apple's 25.6 million, the report said.
The survey also found a steady market share for tablets using Microsoft Windows.
Windows tablet sales rose to 3.4 million from 2.8 million a year earlier, keeping a steady market share of 5.8 percent, according to Strategy Analytics.
"There may be an uptick in Windows following Microsoft's decision to offer Windows for free for sub nine-inch devices," the report noted.
"We may see a new batch of eight-inch Windows-based tablets with reduced prices; they will still not be as inexpensive as Android, but it will enable them to be more competitive and appealing to a wider audience."
But the researchers said a dearth of apps continues to be a problem for Microsoft, "with seemingly little incentive for developers to work on the platform."