Bio-asphalt is a binder that is derived from bio-oil, which is extracted from fast pyrolysis or hydrothermal liquefaction of biomass and petroleum asphalt under specific conditions or by adding other external agents to bio-oil under defined conditions. Due to its renewable and eco-friendly characteristics, bio-asphalt has immense potential to substitute petroleum asphalt and reduce the environmental impact of road construction. This paper provides a comprehensive review of research progress on bio-asphalt, including the preparation and composition of bio-oil, the preparation process and properties of bio-asphalt, modified bio-asphalt, and its modification mechanisms. Future research directions for the development of bio-asphalt are also proposed. The review indicates that most types of bio-oil can improve the low-temperature and fatigue properties of virgin asphalt but may have adverse effects on the high-temperature performance and aging resistance. To improve the performance of bio-asphalt, modifiers such as polymers, rock asphalt, montmorillonite, and nano-clay materials are used to modify bio-asphalt. The majority of existing research is focused on physical modification, with relatively little attention given to chemical and composite modifications. Future studies should focus on the preparation process and classification of bio-oil, the development of efficient modifiers, and the mechanisms of compositemodified bio-asphalt to enhance its quality and increase its proportion of substitution for petroleum asphalt.