A supercontinent forms when all oceanic crust is consumed through plate subduction and nearly all continental blocks on Earth collide each other and coalesce into a single landmass. The assembly of a supercontinent was completed by global- scale continent- continent collision, whereas the breakup of a supercontinent was often caused by the rising of a super- mantle plume. Consequently, such global- scale events that led to the assembly and breakup of a supercontinentwill not only play important roles in the formation and evolution of Earth’s lithosphere, but will also have significant effects on its hydrosphere, atmosphere and biosphere, which will further affect Earth’s habitable environments. During the assembly of a supercontinent, the deep subduction of some continents beneath other continents would decrease the gross areas of continents and thus increase gross areas of oceans, which, as a consequence, causes the subsidence of global sea level. Meanwhile, mantle- derived magmas have less chances to erupt on the surface during the assembly of a supercontinent due to compressive environments, which would decrease CO2 degassed from volcanism and thus lower CO2 contents in the atmosphere, forming the cold- and- dry weather, so- called “Icehouse”, under which glacial tillites can develop in the low latitudinal areas. Such an extreme cold (icehouse) weather is hard for life to survive and may lead to mass- extinction. For example, some researchers regard the P/T boundary mass- extinction as a result of the extreme icehouse weather since it was coincident with the final assembly of Pangea. In contrast, during the breakup of a supercontinent, continental crust undergoes extension and thinning, which increases the gross areas of continents and thus decreases the gross areas of oceans, leading to the rising of global sea level. Moreover, the eruption of voluminous basalts from a super- mantle plume that causes the breakup of a supercontinent will increase CO2 contents in the atmosphere, forming the warm- and- wet weather, so- called “Greenhouse”, which favors the recovery and explosion of life. What deserves mentioning here is that our investigations on the effects of assembly and breakup of supercontinents on the hydrosphere, atmosphere and biosphere are still at preliminary stages, and the above conclusions and implications were mainly based on the environmental effects of the assembly and breakup of Pangea, which need further testing work on the Rodinia and Columbia/Nuna supercontinents.