| JoŽEf | | YAW-zhef | Slovene | |
| JoŽEfa | | YAW-zhe-fah | Slovene | |
| JoŽIca | | - | Slovene, Croatian | |
| Jolanda | | yo-LAHN-dah (Dutch, Italian) | Dutch, Slovene, Croatian, Italian | |
| Josip | | - | Croatian, Slovene | |
| Jozefa | | YO-ze-faw (Hungarian) | Hungarian, Slovene | |
| Julij | | - | Slovene | |
| Julija | | YOO-lee-yah (Slovene) | Slovene, Croatian, Lithuanian | |
| Julijana | | - | Slovene, Croatian, Serbian, Macedonian | |
| Jure | | - | Slovene, Croatian | |
| Jurica | | - | Croatian, Slovene | |
| Jurij | | - | Slovene, Sorbian | |
| Justin | | JUS-tin (English), zhoo-STEN (French) | English, French, Slovene | |
| Justina | | jus-TEE-nə (English) | English, Slovene, Czech, Lithuanian, Late Roman | |
| Kaja (1) | | KAH-yah (Swedish, Estonian) | Norwegian, Danish, Swedish, Estonian, Slovene | |