Piazzi is an Italian surname. Notable people with the surname include:
Charles Piazzi Smyth (1819–1900), British astronomer Fladimir Rufino Piazzi Júnior, (born 1978) Brazilian footballer Giuseppe Piazzi, Italian Theatine monk, mathematician, and astronomer Giuseppe Piazzi (bishop) (1907–1963), Italian bishop Piero Piazzi (born 1963), international fashion modelling manager and talent scout
See also Piazza (surname) Piazzi (crater) Cima Piazzi Spiazzi (disambiguation)