Due to environmental and global warming concerns, sustainable alternatives to traditional materials in the building industry are rapidly gaining in popularity. Historically, the construction industry has relied heavily on steel reinforcement in concrete, however the emissions associated with the production of steel are large, and steel production will need to be drastically reduced (or green steel technologies will need to become commercially available) to meet net zero goals. One way to reduce steel use in construction is to replace steel reinforcement in concrete with sustainable alternatives. While a number of concrete reinforcement alternatives have been proposed and researched, no study has explored which of these are most suitable as replacements for steel across a range of structural, cost and environmental indicators. This study aims to investigate and compare traditional steel reinforcement with emerging sustainable reinforcement types used in concrete, including recycled plastic reinforcement, carbon fibre reinforcement, and natural reinforcement types (bamboo and basalt). To accomplish this, a series of nested systematic literature reviews were conducted on each of these reinforcement types with a focus on strength, cracking control, cost, and carbon emissions. The results of this study show that all of the alternatives to steel for reinforcement have potential applications in industry. However, they all lack the flexural strength of steel, and so are unsuited to situations where flexural loads are limiting. In addition, carbon fibre was shown to be an unsustainable alternative to steel, as its manufacture requires higher carbon emissions than steel, while recycled plastic and natural reinforcement options were shown to be similar or more sustainable than steel. Finally, the study identified a key weakness in the existing literature, in that there are few studies that directly compare different reinforcement types against one another using the same sample characteristics. If alternative reinforcements are to gain popularity, this issue will need to be resolved to improve the clarity of the relative merits of each reinforcement type and what applications they are most suited to.