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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 vrotsin 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.