Detrimental greenhouse gases (GHGs) emissions producing conventional sources of energy are needed to be replaced with eco-friendly and renewable energy sources. Researchers have strongly highlighted biohydrogen is an alternate source of high-energy for alleviating the energy crisis due to its having energy content 2.75 times higher than that of fossil fuels. In addition, the fuel known for leaving no trails of harmful emissions by combustion and emits only water as a by-product. Algal biomass has emerged as a potential feedstock for biohydrogen production. The objectives of the present article is to illustrate the various ways of algal biohydrogen production along with mechanisms and challenges of biohydrogen production in which factors controlling the hydrogen production process and challenges in the economic aspect, technical aspect and storage are considered. Future road map of biohydrogen from algae is also delineated in view of decarbonization pathway and respective SWOT analysis pointing strength, weakness, opportunities and threats. Key strength of algal biohydrogen is identified as excellent carbon capture and waste valorization capability of algae to promote zero-waste circular bioeconomy. Along with these, some weaknesses of this biological approach include technological hinderances leading low biohydrogen yield and high initial cost investment. Implementing genetic/metabolic or environmental manipulations has shown promising opportunity to improve algal biohydrogen to ensure long-term sustainability. Cascading effects of technological immaturity followed by lack of credibility even after suggested alterations are few of threats that need to be superintended by optimizing operational parameters, metabolic engineering, etc. Display omitted •Biological and thermochemical routes have 5.5–6 $/kg and 1.39$/kg for H2 production.•Pre-treatment processes of algal biomass are important step in path of biohydrogen.•Dark fermentation process has emerged as the most studied biological method.•The physiological, genetic/metabolic alterations has potentials to enhance H2 production.•SWOT provided current and future potential of hydrogen production.