In 1825 he aided in establishing the Medical College of South Carolina, and was elected professor of natural history and botany, which he taught until his death in 1830.

[3][5] Elliott engaged in a long and active correspondence with many of the botanists of his time, but wrote an especially large number of letters to Henry Muhlenberg of Pennsylvania.

The material that Elliott collected on numerous field trips and his intimate knowledge of the southeastern flora was of great value to botanists elsewhere.

[6] The US Federal census of 1830 records that both Elliott and his wife had extensive slaveholdings across the South Carolina and Georgia Lowcountry, enslaving 287 people in total.

His classic work, A Sketch of the Botany of South-Carolina and Georgia contained the first botanical descriptions of many species.

"[9] In 1901, Frank Lamson-Scribner wrote the following about Elliott's Sketch: Not until one has prepared a book where almost every line contains a statement of fact learned from original observation can he fully appreciate the amount of patience and labor involved in the preparation of such a work as the Sketch of the Botany of South Carolina and Georgia...today it remains indispensable to the working systematic botanists of our country.