Magnesium (Mg) is the second most abundant intracellular cation and the fourth most abundant mineral in the human body. Mg is involved in multiple biochemical reactions, and its numerous activities are beneficial to our bodies. This review outlines the health significance of Mg in its physiologically beneficial role in function, the sources of dietary Mg along with symptoms of Mg deficiency and the health problems that come from it. Mg is a cofactor in various (more than 300) enzymes and essential for the synthesis of certain neurotransmitters, muscle cells’ capacity to contract and relax, and brain functionality. The proper levels of Mg in cells are achieved through membrane channels and transporters (e.g., TRPM7, MagT1, SLC41A1). These include green leafy vegetables, nuts, seeds, legumes, and whole grains as good sources for Mg. Low levels of such an essential substance in the body can heighten susceptibility to chronic diseases such as metabolic syndrome, Type 2 diabetes, obesity, and cardiovascular morbidity. And inadequate Mg can manifest in symptoms like muscle weakness, fatigue, and cardiac arrhythmias. Not only that, but adequate Mg is needed to maintain bone density and reduce susceptibility to osteoporosis. A sufficient intake of Mg will help to mitigate health problems caused by a deficit of Mg and reduce the incidence of chronic diseases. Healthcare providers need to educate patients on consuming Mg-rich foods and, when indicated, when Mg supplementation is indicated, especially with high-risk individuals and/or those with chronic conditions.