Histones are the fundamental building blocks of chromatin and serve as pivotal regulators of gene expression. Differential expression and mutations of H3.1 and H3.3 genes have been implicated in the pathogenesis of various cancer types. Mutations in H3.3, especially lysine to methionine substitutions (K27M/K36M), are particularly prevalent. Moreover, genetic alterations such as G34R/W/V/L, as well as variations in H3F3A and H3F3B genes, have also been identified. Despite high similarity in amino acid sequences, H3.1 and H3.3 have discrete functions in cancer. In this review, we delve into the recent advances in elucidating the implications of canonical histone H3.1 and its variant H3.3 on chromatin structure and function. Additionally, we explore how potential enhancing factors such as PTEN, MLL5, GPR87 and histone chaperones influence H3.1/H3.3 function.