Hard lead zirconate titanate (PZT) ceramics need more than just continuous extrusion in order for direct ink writing (DIW) to be successful. The printed ring needs to be capable of maintaining filament line shape after shear, restricting inter-strut pathways for liquid-phase transport, avoiding the formation of endpoint defects, densifying without degrading phase formation, and developing piezoelectricity during subsequent poling. This work investigates a range of hard-PZT inks having six different compositions, comprising a base ratio of 50, 52.5, and 55 vol% solids at either 1 or 2 wt% dispersant concentration, to determine whether or not there exists a formulation combination and DIW machine setting that would allow the fabrication of a printed part of high density and similar piezoelectric behavior to die-pressed parts. The full dataset includes formulation ratios, Herschel–Bulkley model parameters, oscillatory yield stress, maximal storage modulus value, extrusion pressure, travel speed, nozzle diameter, line-shape observation, endpoint defect formation, relative density, phase/microstructure observation, and \(d_{33}\). As a full process chain is considered, from suspension preparation to printed ceramic functionality, each ink composition will be evaluated on the basis of the specific problem it causes. The formulations of P50D2 and P52.5D2 are too soft, while P55D1 is too stiff and overly sensitive to pressure. P55D2, on the other hand, represents a compromise between the aforementioned formulations, with high dispersant partitioning and poor printability behavior. Only P52.5D1 is located inside the process window, consisting of 52.5 vol% solids and 1 wt% dispersant, with an oscillatory yield stress of 154.23 Pa, achieving \(G'_{\max}=\SI{146680}{Pa}\), giving a height for printable ink of approximately 3.42 mm, printing through a 420 μm nozzle at 5 mm s−1 and roughly 0.045 MPa extrusion pressure. Sintered at 1200 °C, P52.5D1 prints yield a dense ring with relative density of 97.59 ± 0.46 %, approximately 0.14 percentage points below the die-pressed sample, retaining \(d_{33}\approx\SI{268 \pm 10}{pC/N}\). The main conclusion drawn here is that functional dense hard-PZT DIW can be achieved through a combination of material-motion-sintering window; the ink should recover elastic deformation, the printed line should interact with adjacent filament, and the sintered body should sustain density and piezoelectricity.