We present a Chern-Simons action for $\mathrm{N}=2$ super-Yang-Mills theory in ``full'' $\mathrm{N}=2$ superspace (hyperspace) augmented by coordinates of the internal SU(2) group and show that this action can be reduced to the usual super-Yang-Mills action in the Harmonic () hyperspace. We also discover that the ``choice'' of Harmonic hyperspace is not unique and under suitable conditions, further reduction to the well-known Projective ($\stackrel{\textasciicaron{}}{\ensuremath{\Pi}}$) hyperspace is possible.