He moved to Point Pleasant, New Madrid County, in 1871 and engaged in transportation on the Mississippi River.

He engaged in the dry-goods business at Dexter, Missouri, in 1876, and later, in 1882, in the buying and selling of grain.

Walker was elected as a Democrat to the fiftieth and fifty-first Congresses and served from March 4, 1887, until his death.

He was unanimously nominated as the Democratic candidate for reelection to the fifty-second Congress on the day of his death.

He died July 19, 1890, in Dexter, Missouri from an influenza epidemic that had hit the area.