Sakai most often refers to one of the following:
- Sakai, Osaka, a city in Osaka Prefecture, Japan
- Sakai (name), Japanese surnames written with various kanji
- Sakai Project, an open-source educational and research software project
- Sakai (Malaysian word), a word translated from Malay (Bahasa Malayu) to Chinese slang
It may also refer to:
- Locations
- Sakai, Fukui, a city in Fukui Prefecture, Japan
- Sakai, Fukui (town), a former town and current neighborhood in Sakai, Fukui, Japan
- Sakai, Gunma, a former town in Gunma Prefecture, Japan
- Sakai, Ibaraki, a town in Ibaraki Prefecture, Japan
- Sakai, Nagano, a village in Nagano Prefecture, Japan
- Other
- Sakai (tribe), an indigenous people of the Malay Peninsula
- Sakai bugyō, officials of the Tokugawa shogunate in Edo period Japan
- Sakai clan, a Japanese clan
- Sakai Line, a railway line of West Japan Railway Company between Yonago and Sakaiminato in Tottori Prefecture, Japan
- Sakai Project, a collaboration focused on a course management system
- Sakai Station, a train station on the Nankai Main Line in Sakai, Osaka Prefecture, Japan
- Osaka Blazers Sakai, a men's volleyball team in Sakai, Osaka Prefecture, Japan
- Sakai incident (1868), the killing of 11 French sailors from the French corvette Dupleix in the port of Sakai, Osaka, Japan
- Sakai (Indonesia), one of the tribes in Riau, Indonesia