Around 1.3 billion tonnes of food are wasted worldwide per year, which is originally produced under extensive use of energy and nutrients. Use of food waste as feedstock in biotechnological processes provides an innovative way to recover parts of the energy and nutrients initially spent on food production. By chemical and biological methods, food waste is hydrolysed to glucose, free amino nitrogen and phosphate, which are utilisable as nutrients by many microorganisms whose metabolic versatility enables the production of a wide range of products. Microalgae are particularly of interest as chemicals, materials and energy are obtainable from microalgal biomass after chemical and/or biological modifications. In this review, valorisation of food waste in biotechnological processes is presented as an additional option to green chemical technologies.