The Portable Ladder Platform is an innovative, convenient, sturdy portable ladder accessory for those who use a standard portable straight or extension ladder. The assembled invention provides a comparatively larger platform area for a more comfortable secure stance for anyone needing to work on a ladder for extended time. This invention abandons common platform arrangements that place the user standing outside the ‘safe zone’ (i.e., the area directly over the supporting rung, between the ladder side rails). A creative scheme includes the Locking Handle and the Horizontal Adjustment Screw which together secure the platform to the ladder during use. Emphasis toward user safety is reflected in elements reducing dangerous slipping and promoting platform stability. This ladder platform requires no tools to mount, moves easily and quickly from one level to another, and when mounted does not restrict ladder usage when stepping above or below the platform.