The SkyMapper DR4 (Data Release 4) catalog represents one of the most comprehensive optical photometric surveys of the southern sky to date. Released in February 2024, the DR4 master table (dr4.master) comprises approximately 700 million unique astronomical objects derived from 1.5 billion individual detections, covering an area of 26,000 square degrees extending from the South Celestial Pole to declination δ=+16 degree  (with partial coverage reaching δ=+29 ). Constructed from over 400,000 science-grade images acquired between March 2014 and September 2021 using the 1.3-meter SkyMapper telescope at the Australian National University, the survey operates with a six-filter photometric system (u,v,g,r,i,z ). The typical 10σ  limiting magnitudes range from 18.5 to 20.5 in the AB system, varying by filter bandpass; the deepest co-added regions reach approximately 22nd magnitude, while the bright-end saturation limit is around 9.5 mag. All magnitudes in the SkyMapper survey are reported in the AB magnitude system. To facilitate rapid verification of photometric calibration and ensure continuity with previous data releases, the DR4 master table retains the object identifiers (object_id) from DR2 and DR3 where applicable, assigning new identifiers only to previously uncatalogued sources (starting from 2×10e9 ).