| On Top of the World Golf Club | Ocala | Florida |  United States of America | inactive |
| On Top of the World Golf Club | Clearwater | Florida | United States of America | inactive |
| Onahama Country Club | Iwaki | Fukushima |  Japan | inactive |
| Onahama Ocean Hotel & Golf Club | Iwaki | Fukushima | Japan | inactive |
| Onaping Golf and Beach Club | Onaping | Ontario |  Canada | inactive |
| Onawa Country Club | Onawa | Iowa | United States of America | inactive |
| One&Only Palmilla Golf Club | San Jose del Cabo | Baja California Sur |  Mexico | inactive |
| One-Way Golf Club | Tsuchiura | Ibaraki | Japan | inactive |
| One/Two | Highland | New York | United States of America | inactive |
| Oneida Community Golf Club | Oneida | New York | United States of America | inactive |
| Oneida Golf & Riding Club | Green Bay | Wisconsin | United States of America | inactive |
| Oneida Municipal Golf Course | Oneida | Tennessee | United States of America | inactive |
| Oneka Ridge Golf Course | White Bear Lake | Minnesota | United States of America | inactive |
| Onekaka Links Golf Club | Onekaka | Tasman |  New Zealand | inactive |
| Oneonta Country Club | Oneonta | New York | United States of America | inactive |
| Oneota Golf & Country Club | Decorah | Iowa | United States of America | inactive |
| Onewhero Golf Club | Auckland | Auckland | New Zealand | inactive |
| Onga | Onga | Fukuoka | Japan | inactive |
| Onga Onga Golf Club | Onga Onga | Hawke's Bay | New Zealand | inactive |
| ONGC /Ligripukhuri Golf Club | Nazira | Assam |  India | inactive |
| Ongerup Golf Club | Ongerup | Western Australia |  Australia | inactive |
| Onion Creek Golf Club | Austin | Texas | United States of America | inactive |
| Onishi | Onishi | Gunma | Japan | inactive |
| Onishi Terrace Golf Club | Nakagami | Okinawa | Japan | inactive |
| Onneley Golf Club | Cheshire | Staffordshire |  England | inactive |
| Onneyu Kokusai Country Club | Tokoro | Hokkaido | Japan | inactive |
| Ono Golf Club | Ono | Hyogo | Japan | inactive |
| Ono Grand Country Club | Ono | Hyogo | Japan | inactive |
| Ono Toyo Golf Club | Ono | Hyogo | Japan | inactive |
| Onomichi Country Club - Uneyama Course | Sera | Hiroshima | Japan | inactive |
| Onomichi Golf Club | Mihara | Hiroshima | Japan | inactive |
| Onomichi Uzushio Country Club | Onomichi | Hiroshima | Japan | inactive |
| Onondaga Golf and Country Club | Fayetteville | New York | United States of America | inactive |
| Onsjö Golfklubb | Vänersborg | Västra Götaland |  Sweden | inactive |
| Onsøy Golfklubb | Manstad | Østfold |  Norway | inactive |
| Ontake | Kani | Gifu | Japan | inactive |
| Ontario Country Club | Ontario | New York | United States of America | inactive |
| Onteora Club | Tannersville | New York | United States of America | inactive |
| Ontonagon Golf Course | Ontonagon | Michigan | United States of America | inactive |
| Onuma Kokusai Country Club | Kayabe | Hokkaido | Japan | inactive |
| Onuma Lake Golf Club | Kayabe | Hokkaido | Japan | inactive |
| Onward Mangilao Golf Club | Mangilao | Guam |  Guam | inactive |
| Onward Talofofo Golf Club | Talafofo | Guam | Guam | inactive |
| Onwentsia Club | Lake Forest | Illinois | United States of America | inactive |
| Onyx | Grand Blanc | Michigan | United States of America | inactive |
| Oodate Country Club | Oodate | Akita | Japan | inactive |
| Ooka Golf Club | Kinosaki | Hyogo | Japan | inactive |
| Oonodai Golf Club | Akita | Akita | Japan | inactive |
| Oosaki Golf Club | Shida | Miyagi | Japan | inactive |
| Oost-Zuid | Nunspeet | Gelderland |  Netherlands | inactive |