Green’s Dictionary of Slang

a phr. exhorting someone to ‘go for it’, ‘live life to the full’.

2011		Drake ‘Motto’ 🎵 You only live once, that’s the motto nigga, YOLO.
2012		Game ‘The Logo’ 🎵 You only live once, Y.O.L.O.
2019		www.verywellfamily.com/a-teen-slang-dictionary 10 Mar. 🌐 YOLO - You only live once.