"We're joining the Gmail team to accomplish a bigger vision," Leca said. "While we'll be working on new things at Google, we will continue to make Sparrow available and provide support for our users."
A Sparrow email application for iPhones became available for purchase in Apple's online App Store in March, and a version of the software for Macintosh computers has been available since early last year.
"The Sparrow team has always put their users first by focusing on building a seamlessly simple and intuitive interface for their email client," a Google spokesperson said.
"We look forward to bringing them aboard the Gmail team, where they'll be working on new projects."
Financial terms of the deal were not disclosed.
The acquisition came as Google ramped up software offerings that compete with custom programs that Apple builds into its iPhones, iPads and iPod touch devices.
Google last month took the Web browser battle to iPads and iPhones with the release of Chrome software for popular Apple devices built with Safari online surfing programs at heart.
Safari remains the default browser used in Apple gadgets and the "engine" that Chrome or other Web-surfing applications rely on to function.