Microalgae are photosynthesizing organisms that produce high-value metabolites by using CO₂ as a feedstock, potentially promoting sustainable manufacturing solutions. They are indeed rich in polyunsaturated fatty acids, pigments, polysaccharides, and proteins, which are widely employed in the pharmaceutical, nutraceutical, cosmetic, and food sectors. Among marine diatoms, Phaeodactylum tricornutum is one of the most studied species and commercially suitable strain for large-scale cultivation thanks to its capacity to accumulate commercially relevant metabolites such as EPA, chrysolaminarin, and fucoxanthin. It can successfully operate phototrophy, but mixotrophy mode was revealed to enhance the growth rate and biomass concentration and quality. This review collects recent findings in cultivation strategies and extraction technologies tested on this species so far. The culture performances are discussed and a comparison between mixotrophic and phototrophic conditions is provided. Finally, successful biorefinery extraction cascades experimented on this diatom are described to foster research in this direction.