Haliotis walallensis, common name the flat abalone, is a species of sea snail, a marine gastropod mollusk in the family Haliotidae, abalone.
The shell of Haliotis walallensis is ovate and moderately elevated, reaching up to 120 mm in length. The exterior surface shows coarse growth lines and low spiral ridges, with typically five to seven open respiratory pores along the left side. Shell coloration is variable, ranging from reddish-brown to greenish tones with irregular mottling. The interior is strongly nacreous with iridescent green and blue reflections, characteristic of the genus Haliotis.
This marine species occurs in the Pacific Ocean from British Columbia to Southern California. It inhabits rocky substrates in shallow subtidal waters, similar to other species of Haliotis.