Spiropyran-based dynamic materials have emerged as a promising class of materials due to their ability to respond to various stimuli, including light, temperature, and mechanical stress. This review discusses the synthesis, switching conditions, and applications of dynamic materials where spiropyran is attached to various supports, such as polymers, biomacromolecules, inorganic nanoparticles, and solid surfaces. Spiropyran is a unique molecular switch that undergoes structural isomerisation in response to a variety of stimuli, leading to changes in the properties of the support. The utility of spiropyran as a switch is expected to lead to far-reaching applications in the near future. The spiropyran molecule has two isomers: the closed-ring isomer (SP) and the open-ring isomer (MC). SP is optically transparent in the visible region, while MC absorbs strongly at around 550-600 nm and appears deep blue. The SP and MC isomers have vastly different physicochemical properties, including charge separation, structural differences, optical properties, and emission behavior. The MC isomer is significantly more basic than SP, and its protonation leads to MCH⁺ with a characteristic band at around 420 nm. MC also has a higher affinity for different chemical species, particularly other zwitterions and metal ions. The ability of spiropyran to respond to multiple stimuli, including light, temperature, pH, solvent polarity, redox potential, and mechanical force, makes it a versatile switch. The reversible isomerisation of spiropyran can be achieved through various stimuli, including light, temperature, and mechanical stress. The use of light as a stimulus is particularly advantageous because it allows for precise spatial and temporal control, and it does not introduce chemical contaminants. The isomerisation of spiropyran can also be achieved through near-infrared (NIR) radiation, which is important for applications in biological systems. The aggregation of the open-ring isomer (MC) is an important consequence of its molecular structure. MC can aggregate in hydrophobic solvents due to dipole-dipole interactions and π-π stacking. The aggregation of MC can stabilize the open-ring isomer and thus strongly retard or even block the ring-closing reaction. However, the immobilisation of spiropyran moieties can protect individual MC units from aggregation, allowing for more efficient switching. The immobilisation of spiropyran has several advantages over non-covalent association, including no leaching, improved processability, solvent compatibility, enabling biocompatibility, preventing MC aggregation, reducing photodegradation, improved fluorescence, tailoring the behaviour of the switch, and stabilising ephemeral species. These advantages make spiropyran-based dynamic materials highly suitable for various applications, including smart windows, self-erasing paper, and self-healing coatings. The review also discusses the synthesis and characterization of spiropyran-functionalised polymers, including the photocontrol of polymer fluorescence andSpiropyran-based dynamic materials have emerged as a promising class of materials due to their ability to respond to various stimuli, including light, temperature, and mechanical stress. This review discusses the synthesis, switching conditions, and applications of dynamic materials where spiropyran is attached to various supports, such as polymers, biomacromolecules, inorganic nanoparticles, and solid surfaces. Spiropyran is a unique molecular switch that undergoes structural isomerisation in response to a variety of stimuli, leading to changes in the properties of the support. The utility of spiropyran as a switch is expected to lead to far-reaching applications in the near future. The spiropyran molecule has two isomers: the closed-ring isomer (SP) and the open-ring isomer (MC). SP is optically transparent in the visible region, while MC absorbs strongly at around 550-600 nm and appears deep blue. The SP and MC isomers have vastly different physicochemical properties, including charge separation, structural differences, optical properties, and emission behavior. The MC isomer is significantly more basic than SP, and its protonation leads to MCH⁺ with a characteristic band at around 420 nm. MC also has a higher affinity for different chemical species, particularly other zwitterions and metal ions. The ability of spiropyran to respond to multiple stimuli, including light, temperature, pH, solvent polarity, redox potential, and mechanical force, makes it a versatile switch. The reversible isomerisation of spiropyran can be achieved through various stimuli, including light, temperature, and mechanical stress. The use of light as a stimulus is particularly advantageous because it allows for precise spatial and temporal control, and it does not introduce chemical contaminants. The isomerisation of spiropyran can also be achieved through near-infrared (NIR) radiation, which is important for applications in biological systems. The aggregation of the open-ring isomer (MC) is an important consequence of its molecular structure. MC can aggregate in hydrophobic solvents due to dipole-dipole interactions and π-π stacking. The aggregation of MC can stabilize the open-ring isomer and thus strongly retard or even block the ring-closing reaction. However, the immobilisation of spiropyran moieties can protect individual MC units from aggregation, allowing for more efficient switching. The immobilisation of spiropyran has several advantages over non-covalent association, including no leaching, improved processability, solvent compatibility, enabling biocompatibility, preventing MC aggregation, reducing photodegradation, improved fluorescence, tailoring the behaviour of the switch, and stabilising ephemeral species. These advantages make spiropyran-based dynamic materials highly suitable for various applications, including smart windows, self-erasing paper, and self-healing coatings. The review also discusses the synthesis and characterization of spiropyran-functionalised polymers, including the photocontrol of polymer fluorescence and