  In this paper,we calculate the branching ratios and CP-violating asymmetries
for $B^0 \to \rho^0 \eta^{(\prime)}$ and $B^+\to \rho^+ \etap$ decays in the
perturbative QCD factorization approach. In this approach, we not only
calculate the usual factorizable contributions, but also evaluate the
non-factorizable and annihilation type contributions. Besides the
current-current operators, the contributions from the QCD and electroweak
penguin operators are also taken into account. The theoretical predictions for
the branching ratios are $Br(B^+ \to \rho^+ \eta^{(\prime)}) \approx 9 \times
10^{-6}$ and $Br(B^0 \to \rho^0 \eta^{(\prime)}) \approx 5 \times 10^{-8}$,
which agree well with the measured values and currently available experimental
upper limits. We also predict large CP-violating asymmetries in these decays:
$A_{CP}^{dir}(\rho^\pm \eta)\approx -13 %$, $A_{CP}^{dir}(\rho^\pm
\eta^\prime)\approx -18 %$, $A_{CP}^{dir}(\rho^0 \eta)\approx -41%$,
$A_{CP}^{dir}(\rho^0 \eta^\prime)\approx -27%$, $A_{CP}^{mix}(\rho^0
\eta)\approx +25%$, and $A_{CP}^{mix}(\rho^0 \eta^\prime) \approx +11%$, which
can be tested by the current or future B factory experiments.
