鸟苷（Guanosine）是核苷的一种，是由鸟嘌呤与核糖（呋喃核糖）环组成，两者之间由β-N₉-配糖键相连。

鸟苷经过磷酸化之后可变成鸟苷单磷酸（GMP）、环鸟苷单磷酸（cGMP）、鸟苷双磷酸（GDP）或鸟苷三磷酸（GTP）。

若鸟苷与脱氧核糖相连，则会产生脱氧鸟苷。

Guanosine is a purine nucleoside comprising guanine attached to a ribose (ribofuranose) ring via a β-N₉-glycosidic bond. Guanosine can be phosphorylated to become guanosine monophosphate (GMP), cyclic guanosine monophosphate (cGMP), guanosine diphosphate (GDP), and guanosine triphosphate (GTP). These forms play important roles in various biochemical processes such as synthesis of nucleic acids and proteins, photosynthesis, muscle contraction, and intracellular signal transduction (cGMP). When guanine is attached by its N9 nitrogen to the C1 carbon of a deoxyribose ring it is known as deoxyguanosine.