Huygens accepts a prestigious appointment to the Académie Royale des Sciences in Paris, invited by Jean-Baptiste Colbert. He receives a generous salary and enjoys access to exceptional resources for his research.

During his tenure in Paris, Huygens engages in collaborations with other prominent scientists, including Gottfried Wilhelm Leibniz and Ole Rømer. He continues his research on optics, mechanics, and astronomy, making significant contributions to these fields.

Huygens invents the spiral balance spring for watches, significantly improving their accuracy and portability. Although a similar mechanism was allegedly independently invented by Robert Hooke around the same time, Huygens' version proved commercially successful, revolutionizing watchmaking.

Huygens collaborates with Ole Rømer, who uses observations of the eclipses of Jupiter's moon Io to make the first measurement of the speed of light. This collaboration underscores the international scientific community of the era.

Due to growing political and religious tensions in France (related to the revocation of the Edict of Nantes) and health concerns, Huygens leaves Paris and returns to the Netherlands.