The basic objective of this thesis is to apply techniques of supersymmetric localization for studying Mirror Symmetry in N = 4 gauge theories in three space-time dimensions. We start out by discussing a set of extremely non-trivial checks of Mirror Symmetry for a large class of affine A and D type quiver gauge theories (and their truncated versions) using partition function on a round sphere. Along the way, we discover a one-to-one correspondence between the Type IIB picture of Mirror Symmetry and the aforementioned partition function description. In the next part of the talk, we introduce the idea that a very large class of mirror dual theories may be systematically generated starting from dual pairs consisting only of simple linear quivers by appropriately gauging flavor symmetries on one side of the duality. We discuss some of the remarkable consequences of this construction in understanding the IR behavior of the so-called ``bad" theories of Gaiotto and Witten.