Seismic anisotropy is controlled by aligned rock‐forming minerals, which most studies attribute to solid‐state shear with less consideration for magmatic fabric in plutonic rocks (rigid‐body rotation of crystals in the presence of melt). Our study counters this traditional solid‐state bias by evaluating contributions from fossil magmatic fabric. We collected samples from various tectonic settings, identified mineral orientations with electron backscatter diffraction and neutron diffraction, and calculated their bulk rock elastic properties. Results indicate that magmatic fabric may lead to moderate to strong anisotropy (3%–9%), comparable to solid‐state deformation. Also, magmatically aligned feldspar may cause foliation‐perpendicular fast velocity, a unique orientation that contrasts with a fast foliation typical of solid‐state deformation. Therefore, magmatic fabric may be more relevant to seismic anisotropy than previously recognized. Accordingly, increased considerations of magmatic fabric in arcs, batholiths, and other tectonic settings can change and potentially improve the prediction, observation, and interpretation of crustal seismic anisotropy. Plain Language Summary: Seismic waves that travel through Earth have directionally varying velocities, which depend on the type and orientation of minerals that make up a rock. A common assumption is that the processes that align these minerals occur when the rock is solid, by either brittle fracturing or by plastic deformation at the subatomic scale. However, a similar alignment can form in a magmatic rock by the rotation of elongated crystals in a partially molten rock mush, prior to solidification, and that alignment remains after cooling. In this study, we measured the orientation of such magmatically aligned minerals in rocks and calculated how fast seismic waves travel through the rocks. In some cases seismic properties are similar, whether planar minerals like mica were aligned in the solid‐state or magmatic‐state, with faster seismic waves traveling parallel to the rock's planar fabric. However, where tabular feldspar is strongly aligned in magmatic rocks, seismic waves instead travel faster perpendicular to the rock's planar fabric. Scientists who use seismic stations on Earth's surface to measure differences in crustal seismic velocities can therefore make more accurate interpretations of subsurface rock fabric by considering whether minerals were aligned in a solid‐state or magmatic‐state. Key Points: Magmatic fabric may lead to moderate to strong (3%–9%) anisotropy, comparable to that commonly produced by solid‐state shear deformationMagmatically aligned feldspar causes foliation‐perpendicular fast velocities, contrasting to foliation‐parallel as typical of solid‐stateMagmatic fabrics provide complementary or alternative explanations (compared to solid‐state) for observed crustal anisotropy [ABSTRACT FROM AUTHOR]