The building houses a deli at 48 Russell St. at the intersection of Aqueduct Road.
The unidentified man was in his 40s, Greenburgh Police said.
Detectives from both the White Plains and Greenburgh police departments responded to the scene after the body was discovered at around 6 p.m.
Police say the investigation is in its early stages and more information will be released.
This is a developing story. Check back to Daily Voice for updates.
Click here to follow Daily Voice Mt. Kisco and receive free news updates.