Firefighters responded to the blaze, in the 3900 block of South Cloverdale Street, just after 3 a.m. Monday after receiving multiple calls about flames and smoke at the location.
When crews arrived, they found that residents had evacuated and flames were shooting from the home's second story. The flames were also threatening a home to the west.
Firefighters extinguished the blaze, which extended into the attic, within about a half-hour. They also were able to minimize damage to the neighboring home.
The fire investigator determined the fire caused $100,000 in damage to the home and $40,000 to its contents. The neighboring home sustained about $2,000 in damage.
There were no injuries.
With the determination of arson, the case was turned over the Seattle Police Department's arson bomb squad for further investigation.