He practiced in Boston before joining the U.S. State Department as a law clerk in August of 1924.

He took the Foreign Service examination the first time it was given and received high marks on the written tests.

He also worked in Tananarive, Madagascar, Oporto and Ponta Delgado quintessential posts in the Negro Circuit.

[4][10] In 1953, Wharton was appointed consul general in Marseille, again as the first Black person to hold that position.

After he was assured this was not the case, Wharton accepted the position and became the first Black officer to head a U.S. delegation in Europe.

[12] Loy Henderson, Deputy Undersecretary for Administration wrote to Wharton laterOne of the most unforgettable moments of my Foreign Service life was my conversation with you when you flew from Marseilles to Washington in order to make sure that your appointment as minister to Romania was based on merit and qualifications—not on racial considerations.

At his retirement, Secretary of State Dean Rusk wrote "Yours has been an outstanding career and I am sure you take pride in the fine reputation you have earned.

In 1978, the State Department had a day honoring Wharton and diplomat Lucile Atcherson Curtis, who was the first woman in what became the U.S. Foreign Service.

[14][15] On May 30, 2006, the United States Postal Service issued a stamp depicting Wharton in its Distinguished American Diplomats commemorative series.