Phenolic compounds in olive mill wastewater (OMW) are considered an environmental threat due to their antimicrobial properties. Because of the metabolic versatility of microalgae, a biotic removal of these compounds seems a suitable approach. To investigate the biotic removal of phenolic compounds, the three microalgae species Chlorella vulgaris, Acutodesmus obliquus and Monoraphidium braunii were cultivated in flasks under constant light (50 µmol/m²s) and dark (1 g/L glucose) conditions in presence of different concentrations of OMW. Addition of 1% (v/v) OMW to the culture medium was shown to be non-inhibitory or even growth enhancing, and phenolic compounds were removed by 7–21% by all tested species. Cultivations with 6% (v/v) OMW resulted in a few exceptional experiments in fast growth (C. vulgaris under light, M. braunii under dark conditions) and removal of phenolic compounds (M. braunii, dark). Higher percentages (12 and 25%, v/v) of OMW were inhibitory. Under dark conditions microalgae first consumed glucose and removed phenolic compounds in a diauxic process. Removal of phenolic compounds was favoured under light conditions. Results of this study reveal the opportunities and the challenges of a microalgae-based removal of phenolic compounds and valorization of toxic OMW. Graphic abstract: [Figure not available: see fulltext.]