The production of WWZ at the LHC is an important process to test the quartic gauge couplings of the Standard Model as well as an important background for new physics searches. A good theoretical understanding at next-to-leading order (NLO) is therefore valuable. In this paper, we present the calculation of the NLO electroweak (EW) correction to this channel with on-shell gauge bosons in the final state. It is then combined with the NLO QCD correction to get the most up-to-date prediction. We study the impact of these corrections on the total cross section and some distributions. The NLO EW correction is small for the total cross section but becomes important in the high energy regime for the gauge boson transverse momentum distributions.