The photo was snapped by the New Horizons spacecraft, which is approaching Pluto and scheduled to fly by the tiny world in July 2015, SPACE.com reported Thursday.
Unveiling the photo Wednesday, NASA called it a "major milestone" in the spacecraft's 9-1/2 year voyage to Pluto.
The grainy black-and-white photo shows Charon as a dim object close to but clearly separate from the brighter Pluto.
"The image itself might not look very impressive to the untrained eye, but compared to the discovery images of Charon from Earth, these 'discovery' images from New Horizons look great!" said New Horizons project scientist Hal Weaver of the Johns Hopkins University Applied Physics Laboratory in Laurel, Md.
"We're very excited to see Pluto and Charon as separate objects for the first time from New Horizons."
Charon, at 750 miles wide, is the largest of Pluto's five known moons and obits the dwarf planet at a distance of about 12,000 miles.
The $700 million New Horizons mission was launched in January 2006.