The growth of social media platforms in Thailand, particularly Facebook and YouTube, since the 2010s has created a space and opportunity for amateur archaeologists and art historians to publish surveys, site visits, and opinions to a diversity of Thai society. New narratives and interpretations are broadcasted, reshaping understandings and perceptions of the past in and to society. As examples, the page Prasat Hin Nai Dindaen Thai educates Isan people about their cultural heritage, and not limited to Lao or Thai; Archaeologeek contributes a new archaeological approach, particularly, pop culture in archaeology, to society; Critical Archaeology, created by the author in 2014, aims to criticize social issues regarding archaeology and history; and the YouTube channel Seang Saton Chak A-deed attempts to revise mainstream art history. These social media platforms are changing the landscape of archaeology and art history and the public sphere in Thailand by critiquing a linear history of the nation, decentering archaeological and art evidence information by revealing a diversity of past cultures, and serving archaeological and art information to the public, as an alternative to mainstream narratives. Simultaneously, the Thailand Fine Arts Department has adapted itself by disseminating more knowledge on social media, though this remains in a rather conservative format. This paper aims to illuminate the social phenomena of archaeological and art historical knowledge in Thai society, the emergence of amateur archaeologists and art historians, and demonstrate the impact of social media on public archaeology.