The Boeing-built orbital test vehicle lifted off from the cape Saturday evening and was installed in a low orbit for a mission that has been largely classified.
The launch came a day after Friday's scheduled launch was scrubbed by bad weather.
Boeing Vice President Craig Cooning said in a written statement that the so-called space plane was being monitored by the Air Force Rapid Capabilities Office.
"We took another important step with the successful launch of the second (orbital test vehicle), enabling the RCO to further experiment with the vehicle and its ability to operate in low-Earth orbit," Cooning said.
The X-37B is designed to operate as an unmanned test platform for space research that can land itself at Edwards Air Force Base in California.