Metal–organic frameworks (MOFs) are porous crystalline materials with a high tunability. To improve the functionality of the original frameworks, several strategies, such as the use of different metal cations and organic ligands and post‐synthetic modification, have been developed, enabling the use of MOFs in numerous practical applications in various fields. Recently, another approach, i.e., MOF‐on‐MOF architecturing, has been actively studied by combining two or more MOFs into a composite. MOF‐on‐MOF materials not only possess the intrinsic properties of each MOF but also exhibit unprecedented synergism within a single system, resulting in a considerable potential for various applications. This review summarizes the interesting areas of application of MOF‐on‐MOF architectures into three categories: separation, catalysis, and sensing. In particular, the synergism occurring within such MOF‐on‐MOF architectures is discussed. To improve the functionality of the original frameworks, MOF‐on‐MOF architecturing has been actively studied by combining several MOFs into a composite. This review presents a summary of the application of the MOF‐on‐MOF architectures in separation, catalysis, and sensing. The synergism occurring within such MOF‐on‐MOF architectures is discussed particularly.