Microalgae have a high biotechnological potential due to the bioactive compounds they produce, which are applicable in various commercial sectors, such as human and animal nutrition, pharmaceutical and cosmetic production, biofuel generation, as well as agricultural and industrial inputs. Being photosynthetic organisms, microalgae require light, water, and carbon dioxide. Although more efficient than terrestrial plants, their photosynthetic efficiency remains low (~8–10%) because under normal cultivation conditions (pH > 8.1), the concentration of dissolved carbon dioxide in water is less than 10%, with bicarbonate being the main form of dissolved carbon (>90%). However, microalgae possess the ability to convert bicarbonate into carbon dioxide through the action of the enzyme carbonic anhydrase. This study aimed to test three strategies of bicarbonate addition as an inorganic carbon source for the cultivation of the marine microalga Nannochloropsis oceanica, targeting higher biomass and lipid yields. The strategies tested were: (1) addition at the beginning of cultivation without prior acclimation, (2) addition in the middle of cultivation without prior acclimation, and (3) addition at the beginning of cultivation with prior acclimation. The bicarbonate concentrations tested were 0, 1, 2, and 4 g⋅L⁻¹. The experiments lasted 13 days and were conducted in f/2 medium, using an orbital shaker without aeration. Bicarbonate addition promoted growth, as evidenced by optical density and dry weight measurements. An increase in lipid production was also observed through fluorescence using Nile Red staining. Regarding pigment production, no increase in chlorophyll a concentration was detected. Therefore, all three strategies were effective for enhancing growth and lipid production of N. oceanica, with the acclimated strategy being the least effective for biomass yield but the most promising for lipid generation.