There has been a significant increase in the occurrence of chronic diseases caused by oxidative stress and hypertension in recent decades. Hypertension is a sustained increase in blood pressure and is a controllable risk factor in the development of a number of cardiovascular diseases such as stroke and coronary infarction. As a result, the number of investigations aimed at identification of dietary compounds from natural sources that can be effective in preventing such diseases has increased. Macroalgae, also known as seaweeds or sea vegetables, have been traditionally incorporated into Pacific and Asian foods for hundreds of years and have recently become a popular addition to some Western diets. Macroalgae are classified into three higher taxa according to their pigmentation: brown (Class Phaeophyceae), green (Phylum Chlorophyta) and red (Phylum Rhodophyta). Owing to the harsh environments in which many macroalgae exist, they have developed effective defence mechanisms and, as a result, are a rich source of bioactive compounds, including polysaccharides, polyphenols, fatty acids and peptides, with different structures and activities from those found in terrestrial plants. This review explores the potential use of macroalgal species as bioactive ingredients that could be incorporated into functional foods for use in the prevention and/or treatment of hypertension and oxidative stress-related diseases.