John Mercer Wright was born April 29, 1866 in Calvin, Michigan to Lloyd F. and Sarah (Bird) Wright. The family moved to Lawrence, Kansas, where Wright graduated from high school. He took a special course in accounting at the University of Kansas. In 1888 Wright moved to Topeka. He worked as a teacher at Washington School for two years (1889-1890) and then, when he accepted a post for seven months in 1894, he became one of the first African American clerks in the Topeka post office. Wright was elected Shawnee County Clerk for two terms between 1897 and 1903. He then served as city treasurer for two years before returning to the county clerk's office as first deputy. In both 1929 and 1937, the County Commissioners appointed Wright to serve out the departing county treasurer's unexpired terms.

During World War I, Wright served as executive secretary of the Camp Grant YMCA's War Council. He was also active in a number of organizations including the Masons, the Kansas Republican Party, the Episcopal Church, and the NAACP. Wright served as President of the Topeka Sunday Afternoon Forum and the Interstate Literary Association of Kansas and the West, and as Chair of the latter's Executive Committee. In 1944, Wright was nominated for the NAACP's Spingarn Medal.

Wright married Josephine Rivers of Kansas City.