The test flight reached an altitude of 51.4 miles above the earth - the company's longest ever rocket-powered flight in its quest for space travel - after taking off from the Mojave Air and Space Port.
It was carrying two pilots and four NASA research payloads, as well as a mannequin named Annie, who was acting as a stand-in passenger.
Virgin Galactic's VSS Unity zooms toward space during a rocket-powered test flight on December 13, 2018.
A successful flight will be significant progress toward the start of commercial flights that Virgin Galactic promised more than a decade ago.
Virgin Galactic founder Richard Branson shared the sweet moment on social media, saying, "What better way to propose than with a ring that had just flown to space?"
Four years after Virgin Galactic was established, it promised sub-orbital spaceflight trips for tourists "within 18 months", but delays and a fatal crash in 2014 have created setbacks.
With the advent of commercial companies like Virgin Galactic and Blue Origin eager to give astronaut wings to passengers on their suborbital flights, how to define the boundary is the subject of debate.
The company said that during the flight the spaceship reached Mach 2.9, almost three times the speed of sound, as it touched what it considers to be the edge of space.
Sir Richard Branson is planning to step up production of spaceships and take new passenger bookings as he prepares for the launch of commercial flights as soon as next year.
To accommodate more passengers, Virgin Galactic is building two more spaceships. "When we were in the European Union a couple of years ago the gross national product of Great Britain was the best in Europe - it's now the worst and we haven't even gone into a hard Brexit". "How on earth do I describe the feeling? Joy?"
The two pilots will attempt to launch the craft on a supersonic flight to the edge of space for the first time. The pilots, Frederick Sturckow and Mark Stucky, then burned the rocket motor for 60 seconds to climb upwards at speeds about three times the speed of the sound. Branson said after the flight, "This is a momentous day and I could not be more proud of our teams who together have opened a new chapter of space exploration".
"Reusable vehicles built and operated by private companies are about to transform our business and personal lives in ways which are as yet hard to imagine", Whitesides said. Virgin plans to keep striving to become the first company to offer the public the opportunity to experience zero gravity firsthand, and the opportunity to soar among the stars.