Shares of Responsys spiked nearly 40 percent after being temporarily halted following the announcement.
Oracle's offer of $27 a share represents a 38-percent premium to Responsys' closing price on Thursday. Responsys is a software company that helps marketers run email campaigns.
"Our strategy of combining the leaders across complementary technologies signifies Oracle's overwhelming commitment to winning and serving the CMO better than any other software company in the world," said Mark Hurd, president of Oracle, in a press statement.
Oracle said it expects to close the deal during the first half of 2014.
"Responsys has always been focused on helping marketers realize their largest opportunity—coordinating their marketing touch points across channels, across the customer lifecycle, and across industries, and as a part of Oracle, we will only accelerate our efforts," said Dan Springer, CEO of Responsys.
Oracle shares were slightly lower. (Click here for the latest quote.)
On Wednesday, Oracle posted quarterly results that topped Wall Street expectations, reversing three-straight quarters of revenue misses.
—By CNBC's JeeYeon Park. Follow her on Twitter @JeeYeonParkCNBC.