Born into a noble family, he studied law and met Voltaire in Berlin in 1750 and was taken on as his secretary in April 1752. When Voltaire left the service of Frederick the Great Collini accompanied him, and was confined with him and Madame Denis on Frederick's orders for three weeks in Frankfurt. In 1755 the young Jean-Louis Wagnière was made his assistant, and just over a year later, took Collini's place when he was dismissed from Voltaire's service for insulting Madame Denis.
He then entered the service of Charles Theodore, Elector of Bavaria as his private secretary and historiographer. In 1763 he became a member of the Palatine Academy of Sciences and director of the Mannheim Cabinet of Natural History. In 1764 he was the first person to describe the pterosaur that Georges Cuvier went on the identify, seventeen years later, as a flying reptile.
In his later years, he denounced the fanaticism of the French revolutionary wars and in 1799 he defended the collections in his cabinet from destruction, and managed to have them transferred, four years later, to Munich.
A street in Mannheim is named after him, as is the Collini-Center development in the city.
- Mon séjour auprès de Voltaire (My stay with Voltaire)
- Lettres sur les Allemands (Letters on the Germans)
- Ian Davidson, Voltaire – A Life, Profile Books 2010 p.258
- Ian Davidson, Voltaire – A Life, Profile Books 2010 p.266
- Ian Davidson, Voltaire – A Life, Profile Books 2010 p.272