The picture was snapped by the space agency's Solar Dynamics Observatory (SDO) satellite and shows the sun in ultraviolet light.
NASA says the resemblance to a jack-o'-lantern is caused by "active regions" which appear brighter because they emit more light and energy.
"This image blends together two sets of extreme ultraviolet wavelengths at 171 and 193 Angstroms, typically colorized in gold and yellow, to create a particularly Halloween-like appearance," says the space agency.
It was originally taken in October 2014 but NASA is encouraging users to download it in high resolution to mark Halloween on Thursday.
The 4.5m-high SDO satellite studies the Sun's influence on Earth and Near-Earth space, such as how solar activity is created and the space weather that follows.
