Robert Davis Johnson (August 12, 1883 – October 23, 1961) was a U.S. representative from Missouri.

Born on a farm near Slater, Missouri, Johnson was educated in the rural graded schools of his native county and graduated from the Portland (Indiana) High School in 1901.

He taught school in Saline Valley and Orearville, Missouri from 1901 to 1907.

Johnson was elected as a Democrat to the Seventy-second Congress to fill the vacancy caused by the death of Samuel C. Major and served from September 29, 1931, to March 3, 1933.

He again resumed the practice of law in Marshall, Missouri, where he died October 23, 1961.