Born in 1874, Lankford grew up in Potosi, Missouri. He attended the Lincoln Institute in Jefferson City and Alabama's Tuskegee Institute, taking courses in architectural and mechanical drawing, blacksmithing, carpentry, and engineering. While teaching at the Agricultural and Mechanical Institute in Normal, Alabama, he designed and built steamfitting and sawmill plants and invented a chemical bonding agent used in steel production. Although he never formally studied architecture, he went on to teach architecture and industrial arts at Tuskegee, at Shaw University in North Carolina, and at Ohio's Wilberforce University.

Lankford came to Washington to design and supervise construction of the True Reformers Building at 12th and U Streets, Northwest. That job enabled him to stay in Washington and start the city's first African-American architectural firm. After marrying Charlotte Upshaw, granddaughter of Bishop Henry McNeal Turner of the African Methodist Episcopal Church, he began specializing in church architecture and became the official architect of the AME denomination. His Artistic Churches and Other Designs was the first book on the subject published by a black architect.

A leader in the African-American business community, Lankford served as the first president of the DC chapter of the National Negro Business League. He championed architecture as a field for young blacks and helped convince Howard University to keep its architecture program when trustees voted to drop it in 1933. He went on to combine architecture, real estate, and work for the federal government, before passing away in 1946.

Notes Harry Robinson, dean of Howard's school of architecture and planning, Lankford's contributions were especially significant, considering that he and his colleagues "had no set-asides, no minority-business-enterprise status. They practiced for the institutions supporting their communities.

John Lankford's pioneering work in opening up the profession of architecture to all is his lasting monument in Washington.