The former Fleetwood Mac member is believed to have committed suicide at his home in Nashville, according to The AP.
Nashville police have stated that Welch was discovered by his wife with a self-inflicted gunshot wound to the chest earlier today (June 7).
Welch was a member of Fleetwood Mac from 1971-74, while also forming the group Paris in 1976.
He went on to have a successful solo career, with hits including 'Ebony Eyes' and 'Sentimental Lady'.
'Sentimental Lady' featured backing vocals from Fleetwood Mac's Christine McVie and Lindsey Buckingham.
Police spokesman Don Aaron confirmed that Welch had been suffering from health issues of late, and had left a suicide note.
Bob Welch had in the past described his years with Fleetwood Mac as the "bridge era" between their classic rock 1960s period to their worldwide supergroup status in the mid-to-late 1970s.
He released six solo studio albums between 1977 and 1983.
Watch the video for Bob Welch's 'Sentimental Lady' below: