The integral inequalities have many applications in the mathematics, applications in the ordinary differential equations, partial differential equations, integro-differential equations, fractional differential equations, etc. From these applications, finding the global existence, uniqueness, stability of solutions and other types of applications. In this chapter, we shall give some applications of the integral inequalities in the ordinary differential equations, partial differential equations, fractional differential equations and fractional integro-differential equations. The applications of ordinary differential equations and partial differential equations find a wide range in biological, physical, social and engineering systems. For that reason, we shall adopt the integral inequalities to find the uniqueness of solution to the ordinary differential equations and bounds of solutions to the partial differential equations. Also, we shall use the integral inequalities to find the uniqueness of solution to the fractional differential equations and fractional integro-differential equations. The fractional calculus is a part of mathematics with a long history in earlier work, recently, fractional derivatives have been used in building models of physical processes leading to the formulation of fractional differential equations, the fractional calculus may be considered as an old and yet a novel topic. It is an old topic since, starting from speculation of Leibniz G. (1695-1697) and Euler L. (1730). It had been developed up to now days.In section one, we use Bihari’s and Gronwall’s inequalities to ensure the uniqueness of the solution for the initial value problem which consists of the first ordinary differential equation. In section two, we discuss the uniqueness of the solution for the initial value problem which consists of the fractional differential equation. In section three, we devote Bihari’s and Gronwall’s inequalities to ensure the uniqueness of the solution for the initial value problem which consists of the fractional integro-differential equation.