Pb[(Zr_1/2Ti_1/2)_0.9(Zn_1/3Nb_2/3)_0.1]O₃ (PZT–10PZN) powder was prepared using the columbite precursor method. The phase development of calcined powder precursors was analyzed by X-ray diffraction. Dielectric and ferroelectric properties of the as-sintered and annealed samples were measured and correlated with the microstructure. The morphological evolution was determined by scanning electron microscopy (SEM). The as-sintered ceramic exhibited weak normal-ferroelectric behavior, with a relatively low dielectric constant maximum measured at 1 kHz (ɛ_rmaxat 1 kHz) of 13,000. Annealing resulted in a transition to relaxor-ferroelectric-like behavior, a shift in the dielectric maximum temperature from 360 to 350 °C, and a dramatic increase in ɛ_rmax at 1 kHz to a maximum value of 35,000 for the longer anneal. Furthermore, after thermal annealing at 900 °C for 1 week the composition shifted close to the MPB with a great reduction in the transition temperature and a broadening of the dielectric constant maximum. A strong enhancement of the remanent polarization (P_r) was also observed.