Piru Creek originates as several small springs on the north side of Pine Mountain Ridge in the Santa Ynez Mountains, in the Los Padres National Forest. It flows eastwards through a gentle valley, where it is joined by Cedar Creek from the right. After the Cedar Creek confluence the stream turns northeast, receives Sheep Creek from the left, and Mutau Creek from the right. Piru Creek receives Lockwood Creek from the left at Sunset campground on Lockwood Flat, and flows east into a canyon where the valley walls pull in and rise steeper and higher above the river.