Joshua Brewster Smith (February 9, 1801 – June 17, 1860) was an American politician from New York.
He was the son of State Senator Joshua Smith (1763–1845) and Deborah Smith (1771–1809), and was born and died at the family estate in the Smithtown section of Hauppauge.
He married Mary Rogers (1808–1878), and they had seven children, six of whom died in infancy.
He was a member of the New York State Assembly (Suffolk Co.) in 1839 and 1843.
He was buried at the Hauppauge Rural Cemetery.