Since 1991 Gleiser has taught at Dartmouth College, where he was awarded the Appleton Professorship of Natural Philosophy in 1999, and is currently a professor of physics and astronomy.

Gleiser is the co-discoverer of "oscillons," time-dependent long-lived field configurations which are present in many physical systems from cosmology to vibrating grains.

On 19 March 2019 he received the Templeton Prize for his works exploring the complex relationship between science, philosophy, and religion as complementary pathways for humankind's search for meaning.

[4] In 2024, Gleiser founded a think tank in Tuscany called The Island of Knowledge, dedicated to addressing foundational scientific and philosophical questions and to fostering planetary health and human flourishing.

In September 2023, astrophysicists, including Gleiser, questioned the overall current view of the universe, in the form of the Standard Model of Cosmology, based on the latest James Webb Space Telescope studies.