Carotenoids are hydrophobic pigments with tetraterpene skeleton, widely distributed in higher plants, as well as microalgae from both marine and freshwaters. Animals and humans are unable to synthetize them, and they need to obtain them from dietary sources. The most characteristic feature of carotenoids is the long series of conjugated double bonds forming the central part of the molecule, providing their shape, chemical reactivity, and light-absorbing properties. The colour, ranging from pale yellow to red, and the antioxidant properties of carotenoids highly depend on these conjugated double bonds and other functional groups in the molecule. Food additives are generally divided into six categories: taste enhancers, preservatives, stabilisers, emulsifiers, antioxidants, and colouring agents. This chapter is dedicated to the latter two categories. Carotenoid‐containing plants (e.g. saffron stigmas, pepper pericarps) and their extracts have been used as food colourants for centuries. They are generally considered safe; however, there are only few studies about their stability, biochemistry, bioavailability, pharmacokinetics, and toxicology. Although carotenoids are relatively unstable due to their susceptibility to light, heat, oxygen, autoxidation, and isomerization, there are several commercially synthesized carotenoids (e.g. β‐carotene), which are accepted colour additives. Today, some of the most important carotenoids used as natural colourants in food, feed, and cosmetics industries are produced by microalgae in bioreactors (fermentation technology). Some of the naturally occurring carotenoids (e.g. β-carotene, astaxanthin) are widely commercialised; while others (e.g. lutein, canthaxanthin, zeaxanthin, lycopene) are used less frequently. The global carotenoid market is estimated > USD 2 billion per year, and it is still constantly growing.