This work addresses the problem of infrared mass renormalization for a scalar
electron in a translation-invariant model of non-relativistic QED. We assume
that the interaction of the electron with the quantized electromagnetic field
comprises a fixed ultraviolet regularization and an infrared regularization
parametrized by $\sigma>0$. For the value $p=0$ of the conserved total momentum
of electron and photon field, bounds on the renormalized mass are established
which are uniform in $\sigma\to0$, and the existence of a ground state is
proved. For $|p|>0$ sufficiently small, bounds on the renormalized mass are
derived for any fixed $\sigma>0$. A key ingredient of our proofs is the
operator-theoretic renormalization group using the isospectral smooth Feshbach
map. It provides an explicit, finite algorithm that determines the renormalized
electron mass at $p=0$ to any given precision.