Nutrition plays a crucial role in health promotion and disease prevention, and dietary-related factors are, in many cases, the leading risks for worldwide mortality and morbidity. Nowadays, consumer awareness of this fact has led to an increasing interest in food products that couple both these dimensions to an imperative third overall factor of interest—sustainability. Microalgae and seaweeds have in their composition a wide range of important multifunctional bioactive compounds which may possess cardiovascular protective, anti-inflammatory, anti-hypertensive, antioxidant, anti-coagulant, anti-proliferative, and/or anti-diabetic activities. In addition, they can constitute excellent ingredients for the food industry to be used in the development of value-added food products. This review provides an overview on the current scientific and industrial developments regarding food products incorporating microalgae and seaweeds. Furthermore, technological, nutritional, sustainability, and health benefits resulting from their incorporation in different food matrixes are also explored.