Release Dates
| USA | 1 September 2017 | (Telluride Film Festival) |
| Canada | 10 September 2017 | (Toronto International Film Festival) |
| USA | 5 October 2017 | (Mill Valley Film Festival) |
| USA | 7 October 2017 | (Hamptons International Film Festival) |
| USA | 19 October 2017 | (Middleburg Film Festival) |
| USA | 23 October 2017 | (Philadelphia International Film Festival) |
| USA | 28 October 2017 | (Twin Cities Film Fest) |
| USA | 1 November 2017 | (Austin Film Festival) |
| USA | 2 November 2017 | (Denver International Film Festival) |
| USA | 5 November 2017 | (Hawaii Film Festival) |
| USA | 9 November 2017 | (Coronado Island Film Festival) |
| USA | 12 November 2017 | (St. Louis International Film Festival) |
| Poland | 18 November 2017 | (Camerimage Film Festival) |
| USA | 22 November 2017 | (limited) |
| China | 1 December 2017 | |
| Italy | 1 December 2017 | (Torino Film Festival) |
| France | 2 December 2017 | (Paris) (premiere) |
| United Arab Emirates | 9 December 2017 | (Dubai International Film Festival) |
| USA | 22 December 2017 | |
| France | 3 January 2018 | |
| USA | 3 January 2018 | (Palm Springs International Film Festival) |
| Hong Kong | 4 January 2018 | |
| Israel | 4 January 2018 | |
| Singapore | 4 January 2018 | |
| Taiwan | 5 January 2018 | |
| Australia | 11 January 2018 | |
| Brazil | 11 January 2018 | |
| Czech Republic | 11 January 2018 | |
| Kuwait | 11 January 2018 | |
| Lebanon | 11 January 2018 | |
| Portugal | 11 January 2018 | |
| Slovakia | 11 January 2018 | |
| Spain | 12 January 2018 | |
| UK | 12 January 2018 | |
| Ireland | 12 January 2018 | |
| Norway | 12 January 2018 | |
| Austria | 18 January 2018 | |
| Cyprus | 18 January 2018 | |
| Germany | 18 January 2018 | |
| Greece | 18 January 2018 | |
| Hungary | 18 January 2018 | |
| Italy | 18 January 2018 | |
| South Korea | 18 January 2018 | |
| Netherlands | 18 January 2018 | |
| New Zealand | 18 January 2018 | |
| Peru | 18 January 2018 | |
| Russia | 18 January 2018 | |
| Ukraine | 18 January 2018 | |
| Bulgaria | 19 January 2018 | |
| Finland | 19 January 2018 | |
| Indonesia | 19 January 2018 | |
| Mexico | 19 January 2018 | |
| Romania | 19 January 2018 | |
| Venezuela | 19 January 2018 | |
| Vietnam | 19 January 2018 | |
| Denmark | 25 January 2018 | |
| Uruguay | 25 January 2018 | |
| Poland | 26 January 2018 | |
| Sweden | 27 January 2018 | (Göteborg Film Festival) |
| Malaysia | 31 January 2018 | |
| Estonia | 2 February 2018 | |
| Lithuania | 2 February 2018 | |
| Sweden | 2 February 2018 | |
| Turkey | 2 February 2018 | |
| Philippines | 14 February 2018 | |
| Argentina | 15 February 2018 | |
| Japan | 30 March 2018 |
Also Known As (AKA)
| Argentina | Las horas más oscuras |
| Austria | Die dunkelste Stunde |
| Bulgaria (Bulgarian title) | Най-мрачният час |
| Brazil | O Destino de uma Nação |
| Canada (French title) | L'heure la plus sombre |
| Czech Republic | Nejtemnější hodina |
| Germany | Die dunkelste Stunde |
| Estonia | Süngeim tund |
| Spain | El instante más oscuro |
| Finland | Synkin hetki |
| France | Les heures sombres |
| UK | Darkest Hour |
| Greece (transliterated ISO-LATIN-1 title) | I pio skotini ora |
| Greece | Η πιο σκοτεινή ώρα |
| Hungary | A legsötétebb óra |
| Italy | L'ora più buia |
| Lithuania | Tamsiausia valanda |
| Mexico | Las horas más oscuras |
| Peru | Las horas más oscuras |
| Poland | Czas mroku |
| Portugal | A Hora Mais Negra |
| Romania | Darkest hour. Ziua decisiva |
| Serbia | Najmračniji čas |
| Russia | Темные времена |
| Slovenia | Najtemnejša ura |
| Slovakia | Najtemnejsia hodina |
| Turkey (Turkish title) | En Karanlik Saat |
| Ukraine | Темнi часи |
| USA | Darkest Hour |
| Uruguay (original subtitled version) | Las horas más oscuras |
| Venezuela | Las horas más oscuras |
