He wrote two texts in the field, The Indianized States of Southeast Asia (1968, 1975) (first published in 1948 as Les états hindouisés d'Indochine et d'Indonésie) and The Making of South East Asia (1966), as well as innumerable articles, in which he developed the concept of the Indianized kingdom.

Perhaps his greatest lasting scholarly accomplishment was his work on Sanskrit and Old Khmer inscriptions from Cambodia.

One stele, the recently rediscovered K-127, contains an inscription of what has been dubbed the "Khmer Zero", the first known use of zero in the modern number system.

George Cœdès is credited with rediscovering the former kingdom of Srivijaya, centred on the modern-day Indonesian city of Palembang, but with influence extending from Sumatra through to the Malay Peninsula and Java.

[4] However, due to focusing on the history of lower Southeast Asia, Cœdès was criticized by another historian Tatsuo Hoshino as having underestimated the importance of northern Indochina, Yunnan, and the central Mekong Valley.