During his time as Third Assistant Secretary, Blaine and William Henry Trescot were sent on a special diplomatic mission to South America.

Following the death of Garfield and the resignation of the older Blaine, President Chester A. Arthur appointed Walker Blaine assistant counsel of the United States for the Court of Commissioners of Alabama Claims.

Blaine held this office until the court's abolition on January 1, 1886.

Walker Blaine died in Washington, D.C., unexpectedly on January 15, 1890, of pneumonia that followed a bout of influenza.

[3] He is buried at Oak Hill Cemetery in Washington.