Adults undergo a single spawning event in the winter months, typically in January or February.
Larvae are pelagic and according to laboratory research on other northeastern Pacific Lottia species (L. digitalis and L. asmi), metamorphic competence (at 13ºC) occurs about 5 days after fertilization (Kay and Emlet 2002).
Larvae entrained within coastal currents could potentially be transported long distances (hundreds of kilometers) before settling in the rocky intertidal. Individuals spend approximately two years as juveniles before starting their reproductive lives as male. If they survive and grow long enough, some males will transform into females.
The only sure way of distinguishing males from females is the inspection of the internal gonads for the presence of sperm or egg; there are no secondary sexual characteristics in L. gigantea, except for an educational guess based on their size (females tend to be larger).