A ranar 24 ga Fabrairun 2011, an saki farkon mai haɓaka Lion (11A390) ga masu biyan kuɗi na shirin Apple Developer. An sake sakin sauran masu haɓaka daga baya, tare da Lion Preview 4 (11A480b) wanda aka saki a WWDC 2011. An saki Lion zuwa masana'antu a ranar 1 ga Yuli, 2011, sannan kuma an sake shi ta ƙarshe ta hanyar Mac App Store a ranar 20 ga Yuli, 2011. Apple ya ba da rahoton fiye da miliyan ɗaya na Lion a ranar farko ta fitowa. Ya zuwa Oktoba 2011, Mac OS X Lion ya sayar da fiye da miliyan shida a duk duniya.Lion shine sakin karshe wanda Bertrand Serlet ya kula da ci gabansa, wanda aka ɗauka a matsayin "mahaifin kafa Mac OS X". Tambaya: Yaushe masu biyan kuɗi na shirin Apple Developer suka sami farkon kallon Lion?
24 ga Fabrairu, shekara ta 2011