The increase in the CO concentration in the Earth's atmosphere has been a topic of worldwide concern since anthropogenic emissions of greenhouse gases began increasing considerably during the industrial period. The effects of these mass emissions are probably the main cause of global warming, which has been observed over recent decades. Among the various techniques of CO capture, microalgal biofixation by photosynthesis is considered a promising technology due to the efficiency of these microorganisms in converting this gas into organic compounds through its use as a nutrient in the culture medium. Over the years, several research centers have developed studies on this subject, which have focused on mainly the development of bioreactors, the growth conditions that increase the efficiency of the process and the production of biomass with applicability in several areas. The biological mitigation of CO by microalgae has many advantages, including reductions in the concentration of an industrially sourced greenhouse gas and the energy or food obtained from the produced photosynthetic biomass. This versatility allows for the cultivation of economically useful biomass while reducing the environmental impacts of industrial facilities. In this context, this mini-review aims to discuss new technologies and strategies along with the main challenges and future prospects in the field and the ecological and economic impacts of CO biofixation by microalgae.