Joseph Mendelssohn (August 11, 1770 – November 24, 1848) was a German Jewish banker.
He was the oldest son of the influential philosopher Moses Mendelssohn. In 1795, he founded his own banking house. In 1804, his younger brother Abraham Mendelssohn Bartholdy, the father of the composer Felix Mendelssohn, joined the company. The bank Mendelssohn & Co. continued under the control of the Mendelssohn family and would rise to prominence during the 19th century, becoming one of the most important and influential German banks during the early 20th century. Although the Mendelssohns had largely given up their Jewish religion by 1900, the bank was shut down by the Nazis in 1938 under the policy of Aryanization.