Amazon says it now has more than 150 million Prime members, who pay 119 dollars (£90) a year for faster shipping and other perks.
And its financial results during the busy holiday shopping season were far better than Wall Street analysts expected.
Shares of Amazon.com Inc. soared 12% in after-hours trading on Thursday.
The Seattle-based company reported net income of 3.27 billion dollars (£2.5 billion) or 6.47 dollars (£5) per share, in the three months ending in December. That was up from 3.03 billion dollars (£2.3 billion), or 6.04 dollars (£4.60) per share the year before.
Analysts were expecting earnings of 4.04 dollars (£3.09) per share in the latest quarter, according to research firm FactSet.
Revenue jumped 21% to 87.44 billion dollars (£66.79 billion), also beating expectations.
The last time Amazon revealed how many Prime members it had was in 2018, when it said it had more than 100 million paying members.