Reactive oxygen species (ROS), such as superoxide and hydroxyl radicals, are short-lived molecules with unpaired electrons. They are primarily produced by mitochondria and NADPH oxidase (NOX) and play roles in various physiological processes, including cell signaling and oxygen homeostasis. Recent studies highlight their critical role in UV-induced photodamage of the skin, contributing to exogenous aging, which accounts for 80% of aging. This review discusses the biological characteristics of ROS and their role in regulating UV-induced photodamage, focusing on signaling pathways, particularly those involved in apoptosis. UV radiation is divided into UVC, UVB, and UVA, with UVB and UVA penetrating the ozone layer and causing skin damage through DNA damage, inflammation, oxidative stress, and apoptosis. ROS are generated by various systems, including mitochondria and NOX, and can cause DNA damage, protein oxidation, and lipid peroxidation. ROS levels determine the extent of damage, with low levels causing mutations, medium levels leading to senescence, and high levels causing cell death. ROS are involved in DNA damage, including mtDNA damage, and induce mitochondrial apoptosis. They also disrupt the balance between Bax and Bcl-2 proteins, accelerating cell death. ROS contribute to inflammation by activating MAPK and NF-κB pathways, leading to the release of inflammatory cytokines and the degradation of collagen. ROS also regulate MMPs, which degrade collagen and elastin, leading to skin relaxation and wrinkles. ROS play a key role in UV-induced photodamage by activating signaling pathways that lead to DNA damage, inflammation, and apoptosis. They are involved in the regulation of transcription factors such as AP-1 and NF-κB, which induce the expression of MMPs and inflammatory factors. ROS can also trigger pyroptosis, a form of inflammatory cell death, through inflammasome activation. This review highlights the importance of understanding ROS in UV-induced photodamage, emphasizing their role in inflammation, DNA damage, and apoptosis. The information provided can aid in the development of antioxidants and therapeutic strategies to reduce or prevent photodamage.Reactive oxygen species (ROS), such as superoxide and hydroxyl radicals, are short-lived molecules with unpaired electrons. They are primarily produced by mitochondria and NADPH oxidase (NOX) and play roles in various physiological processes, including cell signaling and oxygen homeostasis. Recent studies highlight their critical role in UV-induced photodamage of the skin, contributing to exogenous aging, which accounts for 80% of aging. This review discusses the biological characteristics of ROS and their role in regulating UV-induced photodamage, focusing on signaling pathways, particularly those involved in apoptosis. UV radiation is divided into UVC, UVB, and UVA, with UVB and UVA penetrating the ozone layer and causing skin damage through DNA damage, inflammation, oxidative stress, and apoptosis. ROS are generated by various systems, including mitochondria and NOX, and can cause DNA damage, protein oxidation, and lipid peroxidation. ROS levels determine the extent of damage, with low levels causing mutations, medium levels leading to senescence, and high levels causing cell death. ROS are involved in DNA damage, including mtDNA damage, and induce mitochondrial apoptosis. They also disrupt the balance between Bax and Bcl-2 proteins, accelerating cell death. ROS contribute to inflammation by activating MAPK and NF-κB pathways, leading to the release of inflammatory cytokines and the degradation of collagen. ROS also regulate MMPs, which degrade collagen and elastin, leading to skin relaxation and wrinkles. ROS play a key role in UV-induced photodamage by activating signaling pathways that lead to DNA damage, inflammation, and apoptosis. They are involved in the regulation of transcription factors such as AP-1 and NF-κB, which induce the expression of MMPs and inflammatory factors. ROS can also trigger pyroptosis, a form of inflammatory cell death, through inflammasome activation. This review highlights the importance of understanding ROS in UV-induced photodamage, emphasizing their role in inflammation, DNA damage, and apoptosis. The information provided can aid in the development of antioxidants and therapeutic strategies to reduce or prevent photodamage.