A pressure-activated ID grooving tool includes a tool body having a channel, a front cross slide slot, a rear cross slide slot projecting, and two legs extending from a piston bore. A piston is disposed within the piston bore. A slide arm has an extension face and a retraction face. A cross slide has a cross slide pocket with a slide engaging face immediately opposing the extension face of the slide arm and a slide retracting face immediately opposing the retraction face of the slide arm. When fluid within the channel and the piston bore is pressurized, the piston moves toward the plunger, which in turn causes the extension face of the slide arm into contact with slide engaging face of the cross slide to cause the cross slide to move in an outward radial direction, thereby pushing the insert into contact with a workpiece.