宇宙中微子背景辐射是由大爆炸产生的中微子构成的背景辐射。与宇宙微波背景辐射类似，它们都是大爆炸的余晖。这些中微子有时又称作“残留中微子”。

宇宙微波背景辐射始于宇宙诞生后379,000年，而宇宙中微子背景辐射则起始于宇宙诞生后2秒钟。据估计，宇宙中微子背景辐射的温度大概为1.95 K；每立方厘米宇宙空间就有大约300个残留中微子存在，但因为低能量中微子和正常物质仅有极其微弱的相互作用，宇宙中微子背景辐射极难检测，也许永远无法直接观测。但是有大量间接证据表明，宇宙中微子背景辐射的确存在。

The cosmic neutrino background (CNB, CνB) is the universe's background particle radiation composed of neutrinos. They are sometimes known as relic neutrinos.

Like the cosmic microwave background radiation (CMB), the CνB is a relic of the big bang; while the CMB dates from when the universe was 379,000 years old, the CνB decoupled from matter when the universe was two seconds old. It is estimated that today, the CνB has a temperature of roughly 7000195000000000000♠1.95 K. Since low-energy neutrinos interact only very weakly with matter, they are notoriously difficult to detect, and the CνB might never be observed directly. There is, however, compelling indirect evidence for its existence.