| Language | Name | Code |
|---|---|---|
| ace | Flensburg | ace |
| Afrikaans | Flensburg | af |
| Aragonese | Flensburg | an |
| Arabic | فلنسبورغ | ar |
| Official Aramaic (700-300 BCE) | ܦܠܢܣܒܘܪܓ | arc |
| Asturian | Flensburgu | ast |
| Azerbaijani | Flensburq | az |
| azb | فلنسبورق | azb |
| ban | Flensburg | ban |
| Belarusian | Фленсбург | be |
| be-tarask | Фленсбург | be-tarask |
| Bulgarian | Фленсбург | bg |
| Bengali | ফ্লেন্সবুর্গ | bn |
| Breton | Flensburg | br |
| Catalan | Flensburg | ca |
| Chechen | Фленсбург | ce |
| Cebuano | Flensburg (kapital sa distrito) | ceb |
| Czech | Flensburg | cs |
| Welsh | Flensburg | cy |
| Danish | Flensborg | da |
| German | Flensburg | de |
| de-ch | Flensburg | de-ch |
| Modern Greek (1453-) | Φλένσμπουργκ | el |
| English | Flensburg | en |
| en-ca | Flensburg | en-ca |
| en-gb | Flensburg | en-gb |
| Esperanto | Flensburg | eo |
| Spanish | Flensburgo | es |
| Estonian | Flensburg | et |
| Basque | Flensburg | eu |
| Persian | فلنسبورگ | fa |
| Finnish | Flensburg | fi |
| fit | Flensburg | fit |
| Faroese | Flensborg | fo |
| French | Flensbourg | fr |
| frr | Flensborag | frr |
| Western Frisian | Flensboarch | fy |
| Irish | Flensburg | ga |
| Galician | Flensburgo | gl |
| Hebrew | פלנסבורג | he |
| Croatian | Flensburg | hr |
| Upper Sorbian | Flensburg | hsb |
| Hungarian | Flensburg | hu |
| Armenian | Ֆլենսբուրգ | hy |
| Interlingua (International Auxiliary Language Association) | Flensburg | ia |
| Indonesian | Flensburg | id |
| Interlingue | Flensburg | ie |
| Icelandic | Flensborg | is |
| Italian | Flensburgo | it |
| Japanese | フレンスブルク | ja |
| Georgian | ფლენსბურგი | ka |
| Kazakh | Фленсбург | kk |
| Korean | 플렌스부르크 | ko |
| Kurdish | Flensburg | ku |
| Kirghiz | Фленсбург | ky |
| Latin | Flensburgum | la |
| Luxembourgish | Flensburg | lb |
| lld | Flensburg | lld |
| lmo | Flensburgh | lmo |
| Lithuanian | Flensburgas | lt |
| Latvian | Flensburga | lv |
| Macedonian | Фленсбург | mk |
| Malay (macrolanguage) | Flensburg | ms |
| Maltese | Flensburg | mt |
| Nauru | Flensburg | na |
| Norwegian Bokmål | Flensburg | nb |
| Low German | Flensborg | nds |
| nds-nl | Flensbörg | nds-nl |
| Nepali (macrolanguage) | फ्लेन्सबर्ग | ne |
| Dutch | Flensburg | nl |
| Norwegian Nynorsk | Flensburg | nn |
| Occitan (post 1500) | Flensburg | oc |
| Ossetian | Фленсбург | os |
| Polish | Flensburg | pl |
| pnb | فلنزبرگ | pnb |
| Portuguese | Flensburgo | pt |
| pt-br | Flensburg | pt-br |
| Romanian | Flensburg | ro |
| Russian | Фленсбург | ru |
| Scots | Flensburg | sco |
| sh | Flensburg | sh |
| Slovak | Flensburg | sk |
| Slovenian | Flensburg | sl |
| Albanian | Flensburg | sq |
| Serbian | Флензбург | sr |
| stq | Flensbuurich | stq |
| Swedish | Flensburg | sv |
| Swahili (macrolanguage) | Flensburg | sw |
| Thai | เฟล็นส์บวร์ค | th |
| Turkish | Flensburg | tr |
| Tatar | Фленсбург | tt |
| tum | Flensburg | tum |
| Ukrainian | Фленсбург | uk |
| Uzbek | Flensburg | uz |
| Vietnamese | Flensburg | vi |
| Volapük | Flensburg | vo |
| war | Flensburg | war |
| Wu Chinese | 弗伦斯堡 | wuu |
| xmf | ფლენსბურგი | xmf |
| yue | 弗倫斯堡 | yue |
| Chinese | 弗伦斯堡 | zh |
| zh-cn | 佛伦斯堡 | zh-cn |
| zh-hans | 佛伦斯堡 | zh-hans |
| zh-hant | 佛倫斯堡 | zh-hant |