No cause of death was released, and police said an investigation continues.
Police said a man called 911 to report having found Stephen "Greg" Fisk deceased inside his downtown residence at about 3:34 p.m.
Fisk was elected mayor last month, ousting incumbent mayor Merrill Sanford in a campaign which was notable for its lack of rancor, with both candidates regularly praising each other.
City and Borough of Juneau officials Monday canceled a meeting of the city assembly that has been scheduled for Monday evening.
(c)2015 the Alaska Dispatch News (Anchorage, Alaska)