Johann Friedrich Hennert (19 October 1733 – 30 March 1813) was German-born and lectured in mathematics and physics at the University of Utrecht. He was a significant student of Leonhard Euler. He was known for his inclination towards the British school of philosophy.

Hennert held the chair of mathematics at the University of Utrecht until 1805.

Hennert was an important figure in the history of Dutch mathematics. He wrote a number of textbooks on differential calculus.

Jan van Swinden was one of his most important students.

• van Berkel, Klaas; van Helden, Albert & Palm, L. C. (1998). A History of Science in the Netherlands: Survey, Themes and Reference. Leiden: Brill. ISBN 90-04-10006-7.
• Helmers Dini M., Timmerman, Petronella Johanna de, in: Digitaal Vrouwenlexicon van Nederland.

• Johann Friedrich Hennert at the Mathematics Genealogy Project