  The asymptotic symmetry algebra of $\mathcal{N}=1$ supergravity was recently
constructed using the well-known $2$D celestial CFT (CCFT) technique in ArXiv:
2007.03785. In this paper, we extend the construction to the maximally
supersymmetric four dimensional $\mathcal{N}=8$ supergravity theory in
asymptotically flat spacetime and construct the extended asymptotic symmetry
algebra, which we call $\mathcal{N}=8$ $\mathfrak{sbms}_4$. We use the
celestial CFT technique to find the appropriate currents for extensions of
$\mathcal{N}=8$ super-Poincar\'{e} and $\mathrm{SU}(8)_R$ R-symmetry current
algebra on the celestial sphere $\mathcal{CS}^2$. We generalise the definition
of shadow transformations and show that there is \textit{no} infinite
dimensional extension of the global $\mathrm{SU}(8)_R$ algebra in the theory.
