William W. Thayer introduced him to Mary Richardson, who also wanted to serve as a missionary.

From August 1838 to June 1848, under the auspices of American Board of Commissioners for Foreign Missions, he and Cushing Eells and their wives created and lived at the Tshimakain Mission, studying the local language and bringing their Protestant faith to the Spokane People.

Elkanah Walker and Cushing Eells were supposed to be at the Whitman Mission during the time of the massacre, but Elkanah Walker became sick, and Cushing Eells did not want to leave the families without support with during winter.

[6] After arriving in Oregon City, Elkanah Walker purchased a wagon on credit and began freighting goods.

He and his family moved to Forest Grove, Oregon in October 1849, where he purchased a donation land claim.