Jakob Sigismund von Reinach-Steinbrunn (1683–1743) was the Prince-Bishop of Basel from 1737 to 1743.
Jakob Sigismund von Reinach-Steinbrunn was born in Obersteinbrunn, the son of Johann Jakob Kaspar Sigmund Freiherr von Reinach-Steinbrunn (d. 1693) and his wife Maria Salome Lucia von Pfirt (d. 1721).
From 1703 to 1705, he attended the Jesuit gymnasium in Porrentruy. He then studied Christian theology at the Collegium Germanicum in Rome.
He became a canon in 1707, and was ordained as a priest on September 18, 1717. He became the provost of Basel Münster in 1726.
On June 4, 1737, the cathedral chapter of Basel Münster elected him to be the new Prince-Bishop of Basel, with Pope Clement XII confirming his appointment on September 30, 1737. He was consecrated as a bishop by Cardinal Barni on June 29, 1738.
He died on December 16, 1743.