Additives which share a similar molecular structure with the crystallizing parent molecule are called tailor-made additives (TMAs). The inclusion of well-chosen TMAs often has a significant impact on crystallization behaviors. However, how TMAs affect the solution crystallization has seldom been systematically summarized in recent years. Herein this paper reviews the role of TMAs in solution crystallization. First, the effects and action mechanisms of TMAs on crystal nucleation and growth are discussed, respectively. Next, the applications of TMAs in the regulation of crystal properties including the polymorphism, crystal habit, crystal size, and chirality are introduced. Then the recent progress of molecular simulation in predicting the role of TMAs is discussed. Finally, we analyze the existing problems in this field and give an outlook on the future development. This paper is helpful and useful to readers interested in the use of TMAs to control crystallization and design crystals with desired properties.