The third version of the XMM-Newton slew survey catalogue, XMMSL3, was released on 19th February 2025 by the XMM-Newton Survey Science Centre (XMM-SSC) in collaboration with the SOC. This version includes an extra 8.5 years of data, there are 140735 X-ray detections, which relate to 116598 unique sources, doubling the number of detections available in the previous version, XMMSL2. This catalogue version covers more than 90% of the sky, where some regions of the sky have been pointed as many as 78 times. Around 8% of all the detections are classified as extended. The median positional uncertainty of the catalogue detections is 13 arcseconds. Mean fluxes in the catalogue are ~2.8E-12 and ~6.5E-11 erg/cm²/s in the soft (0.2-2 keV) and hard (2-12 keV) X-ray bands, respectively.