From 1907–1913, the Governor of the Territory of Hawaii was Walter F. Frear who was married to Dillingham's sister Mary Emma.

[4] Dillingham served on several commissions for the Territory of Hawaii, including the tax appeal court 1908–1910.

[5] In 1919, Dillingham built a large house at Papaʻenaʻena, an ancient Hawaiian altar to the surf and place of human sacrifice to the god Kūkaʻilimoku, on the slopes of Diamond Head.

Dillingham drained the wetlands of Waikīkī in the early 1920s and created the Ala Wai Canal, on whose banks the Hawaiʻi Convention Center was built.

The Hawaiian Sugar Planters' Association-sponsored commission petitioned the U.S. Senate to lift an 1882 ban on importing workers from China, hoping to use Chinese migrant laborers to replace the Japanese and break the strike.

[7] His son Benjamin Franklin Dillingham II (1916–1998) ran with the Hawaii Republican Party against Daniel Inouye for the Senate in 1962 and lieutenant governor in 1974[8] but lost both elections.