The X-ray polarization of Sco X-1 was measured for the first time with very high significance by the Imaging X-ray Polarimeter Explorer (IXPE). A polarization degree of $1.0\% \pm 0.2\%$ at a PA of $8° \pm 6°$ at $90\%$ CL in the 2-8 keV energy band is obtained, while the source was in its soft state with short flaring periods. The source state was determined by a strictly simultaneous X-ray observation campaign jointly with \ixpe, which involved \nicer, \nustar, and \hxmt, allowing for a broad-band spectrum characterization and study of quasiperiodic oscillations. The spectropolarimetric analysis yielded a polarization of ${<}3.2\%$ for the accretion disk and a polarization of $1.3\% \pm 0.4\%$ for the hard Comptonized component. A constraint on the polarization of the reflection component, modeled using relxillNS, is obtained. All the results about the polarization degree match the theoretical expectations, while the polarization angle of $8° \pm 6°$ at $90\%$ CL shows a rotation of $46° \pm 9°$ with respect to the measured position angle of the radio jet and previous marginal results by PolarLight. This may suggest a variation in the polarization angle related to the source state, which is linked to the variation of corona geometry as reported by IXPE observations of Z sources, or possibly to relativistic precession.