Giovanni Battista Rezzonico (1 June 1740 – 23 February 1785) was an Italian cardinal of the Catholic Church.
He was the nephew of Pope Clement XIII (Carlo della Torre di Rezzonico or Carlo Rezzonico Senior) (1602–1680).
On 10 September 1770, he was named a cardinal by Clement XIV and installed on 12 December 1770.
He died as Cardinal-Deacon of San Nicola in Carcere.
[2][3] In the 1760s, he engaged Giovanni Battista Piranesi to enhance the structure of Rome's Santa Maria del Priorato Church and its plaza, providing both with new decoration.