In this dissertation, shape- and composition-controlled noble metal nanocatalysts were synthesized for improving electrocatalytic properties toward oxygen reduction and oxygen evolution reaction in $Li-O_2$ battery and alcohol oxidation reaction in direct alcohol fuel cells. In addition, development of facile synthesis method for preparing shape- and composition-controlled noble metal nanocatalysts and their growth mechanism were also described. In chapter 2, chestnut-bur-like palladium nanocatalysts were synthesized in high yield by using cetylpyridinium chloride as stabilizer and their growth mechanism was investigated. In chapter 3, highly branched palladium nanodendrites supported on graphene were prepared and applied as cathode catalysts in Li-oxygen battery. In chapter 4, 1-dimensional Pt nanochains with enhanced electrocatalytic activity and durability were prepared through facile solution-phase synthesis method. In chapter 5, composition-controlled PtPd alloy nanocatalysts were synthesized on graphene through the introduction of bifunctional materials, which can be used to modify the GNP surface and simultaneously reduce metal ions. The prepared noble metal nanocatalysts in this dissertation were synthesized via facile solution-phase synthesis method and they exhibited enhanced electrocatalytic properties for alcohol oxidation reaction or oxygen reduction/evolution reactions.