Born in Basel in 1744 (4 November).
Johann was the son of Johann(II) Bernoulli. He was certainly considered a prodigy when a child with an encyclopedic knowledge and, like several other members of his family, he studied law and took an interest in mathematics.
At the early age of fourteen he gained his magister in law.
In 1763 he fully qualified in law with a dissertation containing both maths and law
He had studied maths and astronomy under his uncle Daniel.
He was appointed to a chair of Mathematics at Berlin Academy at the age of only 19, at the end of the Seven Years War.
He arrived in Berlin 1764, to be greeted by Euler and his sons.
At twenty years old he was invited by Friedrich II (the so-called Great) to reorganize and revive the Astronomical Observatory of Berlin Academy, but seemingly this was a task for which Johann was not particularly well suited. His health had never been particularly good and his qualities as an astronomical observer were relatively poor. He wrote a number of works on astronomy, reporting on astronomical observations and calculations, but these are of little importance. Strangely his most important contributions were the accounts of his travels in Germany which were to have a historical impact.
He journeyed to London, Paris, returned to Basel where he married and returned to Berlin in 1769.
1769 became Royal Astronomer
In the field of mathematics he worked on probability, recurring decimals and the theory of equations. As in his astronomical work there was little of lasting importance. With Hindenburg , however, he did publish the Leipziger Magazin für reine and angewandte Mathematik (Leipzig Journal for Pure and Applied Mathematics) between 1776 and 1789.
In 1774 he published a French translation of Leonhard Eulerís Elements of Algebra.
He was very concious of the famous mathematical line from which he was descended and he cared for their wealth of mathematical writings. He sold the letters to the Stockholm Academy where however they lay forgotten until 1877. When they were examined, 2800 letters written by Johann(III) Bernoulli himself were found in the collection.
He managed the estate of Johann Lambert.
He became the director of the Mathematics Section of the Berlin Academy.
He died on 13 July 1807 in Berlin-Köpenick.