Due to its distinct electrical structure and environmental compatibility, graphitic carbon nitride (g-C3N4) has become a viable photocatalyst for various applications. Significant initiatives are currently being implemented to enhance the photocatalytic activity of g-C(3)N(4 )by adding oxygen dopants to its structure. The unique characteristics of oxygen-doped g-C3N4(O@g-C3N4), including enhanced charge carrier mobility and changed electronic structure, make it especially appealing for photocatalytic applications. The synthetic techniques used to create O@g-C(3)N(4 )are thoroughly examined in this paper, along with the structural changes brought on by oxygen doping and the processes underpinning its increased photocatalytic activity. The methods for adding oxygen atoms to the g-C(3)N(4 )lattice are covered in the synthesis section, including solid-state processes, chemical vapor deposition, hydrothermal synthesis, co-precipitation, and post-treatment procedures. Using these techniques, the type and density of oxygen functional groups may be precisely controlled, allowing O@g-C3N4's photocatalytic characteristics to be tailored. O@g-C3N4's characteristics are discussed, emphasizing its modified electronic band structure, better surface reactivity, and enhanced light absorption abilities. Recent developments in the field are also presented, exhibiting cutting-edge techniques, including heteroatom doping, nanostructuring, and co-catalyst integration that further enhance O@g-C3N4's photocatalytic capabilities. As a versatile photocatalyst, O@g-C(3)N(4 )has been extensively reviewed in this study, emphasizing its synthesis processes, structural characteristics, and current developments in improving its photocatalytic activity. Our understanding of O@g-C(3)N(4 )is deepened by this review's insights, which also open the door for future research into using the compound in environmentally friendly and sustainable technology.