Cultural heritage embodies the true significance of cultural development processes. It serves as a positive representation of historical traditions that form a national identity passed down through generations. A considerable number of these cultural and natural artifacts are crafted from wood or similar cellulosic materials, which are relatively durable, yet susceptible to concurrent deterioration, presenting challenges for their preservation and upkeep. Biodeterioration, such as decay caused by fungi, threatens these invaluable treasures, particularly affecting wooden cultural or natural monuments and religious artifacts. Wood rot in wooden natural and cultural monuments and artifacts across Southeast Asia is caused by fungal species generally under three divisions, namely, Ascomycota, Basidiomycota, and Mucoromycota. The diverse lifestyle and extensive enzymatic systems of fungi enable them to thrive even in often extremophilic conditions associated with cultural heritage and the built environments. In Southeast Asia, traditional knowledge has significantly contributed to the preservation of historic wooden structures by offering insights into the timing and types of trees designated for use, and also provides guidance on which organic materials can be employed as fungicides. A variety of repair methods and chemicals, including carbon disulfide and thymol, as well as a 10% thymol solution in alcohol or ether for fungicidal purposes, are utilized for wood-based paper conservation. The architectural marvels of wooden-built heritage exhibit intricate details and are rich in historical milieu; hence, it necessitates more extensive studies on microbial communities contributing to the complexities of biodeterioration to gain a comprehensive understanding of the biodegradative processes and effective conservation methods for these valuable cultural assets.