Johnny Weltz (born 20 March 1962) is a Danish retired road bicycle racer. He rode most of his career for the Spanish ONCE team.

In 1985 he won silver at the world championship for amateurs. The high point of his career was his victory at stage 19 (a mountain stage) of the 1988 Tour de France, and was 54 overall. He also won a stage in Vuelta a España the same year.

After his active career, he worked in various capacities for the professional teams Motorola, U.S. Postal Service, and Team CSC (back then called MemoryCard – Jack&Jones, and later CSC – World Online). Weltz was most recently a directeur sportif with Team Slipstream.