Karl Gotthelf Lehmann (7 March 1812 in Leipzig – 6 January 1863 in Jena) was a German physiological chemist.
From 1830 he studied medicine at the University of Leipzig, receiving his doctorate in 1835 with a thesis titled De urina diabetica.
In 1842 he became an associate professor of medicine at Leipzig, where in 1854 he was named a full professor of physiological chemistry.
From 1856 to 1863 he was a professor of general chemistry at the University of Jena.