Histone crotonylation is a recently described post-translational modification that occurs at multiple identified histone lysine crotonylation sites. An increasing number of studies have demonstrated that histone crotonylation at DNA regulatory elements plays an important role in the activation of gene transcription. However, among others, we have shown that elevated cellular crotonylation levels result in the inhibition of endocytosis-related gene expression and pro-growth gene expression, implicating the complexity of histone crotonylation in gene regulation. Therefore, it is important to understand how histone crotonylation is regulated and how it, in turn, regulates the expression of its target genes. In this review, we summarize the regulatory factors that control histone crotonylation and discuss the role of different histone crotonylation sites in regulating gene expression, while providing novel insights into the central role of histone crotonylation in gene regulation.