Carbon storage is one of the most important ecosystem services provided by kelp beds. Laminarialean kelps are widely harvested along the Warm Temperate South-eastern Pacific coast, a marine province shared by Chile and Peru. Carbon storage assessments of kelps in Peru are lacking. From a blue economy and sustainable management perspectives, information on the carbon storage of kelps is important. We conduct the first carbon storage assessment of Lessonia trabeculata in Peru and contribute to the development of biomass estimation models in order to monitor kelps using the least destructive methodologies. We chose three commonly harvested sites in San Juan de Marcona to haphazardly extract Lessonia trabeculata sporophytes using transects. Sporophyte height (m), wet biomass (kg), maximum (D) and minimum (d) holdfast disk widths (cm) were measured in the field. In the laboratory, C content was measured to calculate the best-fitting coefficients for future estimations by using allometric equations. Individual biomass was best estimated from sporophyte height through a rational model, while holdfast area (ellipse in cm2) was a good proxy of biomass with a sinusoidal model. The southernmost, least accessible, and most exposed site (Elefante) had significantly higher values of stored carbon. We estimated a carbon standing stock (from sporophytes only) of 2044 t C in these kelp beds. Nevertheless, additional and more detailed measurements will likely produce more accurate estimates both in time and space. We provide allometric equations for future carbon assessments. Our results highlight the importance carbon assessment for kelp management and blue carbon estimates and the need to develop science-based marine planning strategies.