<p>Phase equilibria in the nickel-rich corner of the Hf–Ni–Ti system were studied using physicochemical analysis methods, including differential thermal analysis, scanning electron microscopy, electron probe microanalysis, and X-ray diffraction. The liquidus and solidus projections, isothermal sections at 1000 and 700°C, and a vertical section along the 87.5 at.% Ni isopleth were constructed. This revealed the features of phase transformations over a wide temperature range in the Hf₂Ni₇–Ni–TiNi₃ region. The results confirmed the presence of invariant four-phase L ⇄ (Ni) + HfNi₅ + TiNi₃ and L ⇄ HfNi₅ + TiNi₃ + Hf₂Ni₇ eutectic transformations in this region at 1215 and 1200°C, respectively. Differences between our liquidus projection and previously published versions based on thermodynamic modeling were discussed. Alternative nature of the equilibria was established at 1000 and 700°C as compared to the solidus projection. The nature of the equilibria was found to change between 1200 and 1000°C through the solid-state (Ni) + Hf₂Ni₇ ⇄ HfNi₅ + TiNi₃ transformation. The microstructure of samples from all primary crystallization regions was analyzed. The samples from the TiNi₃ primary crystallization region crystallized in a nonequilibrium way, contributing to the glass formation in eutectic melts. The research is novel in that it fills gaps in experimental data for the high-nickel composition range. This is an important step toward further predicting the glass-forming ability of multicomponent alloys and optimizing their chemical composition for practical applications.</p>