Or at least, as nearly perfect as can be currently measured by human instruments. According to Edward Hines and his colleagues from the Imperial College London, if a single electron were inflated to the size of our solar system, it would not deviate from perfect sphericality by the width of a human hair.
The physicists took electrons from ytterbium fluoride molecules and subjected them to a finely tuned laser. The energy from that laser causes the electrons to move in specific ways. A spherical electron will rotate differently than an egg-shaped electron, which will tend to wobble. To the limits of their detection capacities, the researchers found no wobble at all. In fact, the complete lack of wobble translates to a difference of less than 0.000000000000000000000000001 cm from being a perfectly sphere. And it could turn out to be a lot less if we still don't detect any wobble as our measuring skills improve.
This data has repercussions for understanding how the universe came to be constructed the way it is. More specifically, the spherical nature of electrons may play a role in determining what happened to all the anti-matter that was presumably formed along with regular matter during the Big Bang.