  The reduced density matrix of many-body systems possessing an additive
conserved quantity can be decomposed in orthogonal sectors which can be
independently analyzed. Recently, these have been proven to equally contribute
to entanglement entropy for one dimensional conformal and integrable systems.
In this paper, we extend this equipartition theorem to the disordered critical
systems by studying the random singlet phase. We analytically compute the
disorder averaged symmetry resolved R\'enyi entropies and show the leading
orders are independent of the symmetry sector. Our findings are cross-checked
with simulations within the numerical strong disorder renormalization group. We
also identify the first subleading term breaking equipartition which is of the
form $s^2/\ln\ell$ where $s$ is the magnetization of a subsystem of length
$\ell$.
