The California-based company said on Wednesday it had a net income of $692 million on revenue that rose 23 percent to $3.4 billion in the quarter that ended June 30.
The profit represented a 144 percent increase from the same three-month period last year.
"We delivered a great second quarter," said eBay chief executive John Donahoe.
"Our entire company is strong, but we're particularly pleased with eBay Marketplaces."
eBay shares jumped more than five percent to $42.59 in after-market trading that followed release of the earnings figures.
Along with its Marketplaces platform for people and small businesses to sell items online, Donahoe credited the strong results to the PayPal online financial transactions platform and its GSI e-commerce services arm.
"Mobile continues to be a game-changer," Donahoe said, referring to how people are increasingly relying on smartphones for shopping, banking and other personal business.
"We now expect eBay and PayPal mobile to each transact $10 billion in volume in 2012 -- that's more than double 2011, a staggering surge in mobile shopping and payments on devices that did not exist just a few years ago."
The PayPal Here mobile payment system for small businesses became generally available in Hong Kong and the United States on Wednesday, according to eBay.
PayPal Here uses a triangle-shaped "dongle" card reader that plugs into mobile devices to act as a credit card reader for consummating purchases.
PayPal Here software also lets shopkeepers take payments by snapping pictures of credit cards with smartphones instead of having to swipe them in dongles.
There are more than 113 million active PayPal customers globally, according to PayPal president David Marcus. More than half of PayPal's revenue in the recent quarter came from outside the United States.
The retail industry is at an inflection point with mobile gadgets "becoming the digital nexus of people's lives," Donahoe contended.
Donahoe cited the earnings, which topped Wall Street expectations, as proof that eBay has revitalized its core Marketplaces business of serving as an online bazaar for buyers and sellers of all types.
"It represents a turn-around of sorts," said Forrester analyst Brian Walker.
"For quite some time eBay was struggling to satisfy smaller merchants while trying to attract bigger sellers."
A powerful engine for eBay profit remained PayPal, which faces competition in an array of regions, from Square in the US to Alipay in China.
"PayPal has been the growth driver at eBay for years, and that may not necessarily continue," the analyst said.
"The key issue will be whether PayPal can compete in a war in mobile against the likes of Square and others including traditional in-store payment system providers that are coming up with solutions of their own."
PayPal on Tuesday announced that it has bought San Francisco startup Card.io, which specializes in technology that lets people use smartphone cameras to take payments by snapping pictures of credit cards.
"You can envision a world in the not too distant future where you can just take a picture of your driver's license and credit cards to open a PayPal account," Donahoe said.
PayPal has been ramping up services tailored for mobile devices as smartphones and tablet computers are ever more important in modern lifestyles.