The fire broke out at the El Dorado Mobile Home Park just before 10 p.m. Monday.
Firefighters found two people inside the home; a 71-year-old man died at the scene and a 67-year-old woman was rushed to the hospital.
The name of the man who died has not been released.
No other injuries have been reported.
UPDATE on the fatal fire in #Sunnyvale this morning: A 71 y/o man was killed in the fire. A 67 y/o woman is in critical condition at the hospital. Cause is still under investigation @abc7newsbayarea https://t.co/HS3cVYewUt— Julian Glover (@JulianGABC7) January 21, 2020