We present a dynamical study of the eclipsing intermediate polar XY Ari based on time-resolved near-infrared spectroscopy obtained with the EMIR spectrograph on the 10.4-m Gran Telescopio Canarias. Using main sequence template spectra taken with the same instrument setup as the target spectra, we measure a radial velocity amplitude of the late K- type donor star K₂ = 256 ± 2 km s^-1. We also obtain the rotational broadening of its photospheric lines v_rot sin i = 141 ± 3 km s^-1. From these and the eclipse geometry, we derive a donor-to-white dwarf mass ratio q = M₂/M₁ = 0.62 ± 0.02, an orbital inclination i = 80.8° ± 0.5° and dynamical masses M₁ = 1.21 ± 0.04 M_⊙ and M₂ = 0.75 ± 0.04 M_⊙ (1σ). This result places the white dwarf in XY Ari as one of the three most massive known in a cataclysmic variable. Comparison with white dwarf mass estimates from X-ray spectral studies could indicate the necessity of an improvement of the X-ray models and/or analysis techniques, as a number of X-ray white dwarf masses are in disagreement with the dynamical mass value.