Nogometni klub Celje (English: Celje Football Club), commonly referred to as NK Celje or simply Celje ([ˈtsɛ̀ːljɛ]), is a professional football club from Celje, Slovenia. They play in the Slovenian PrvaLiga, the top tier of Slovenian football. Together with Maribor, they are the only club that have participated in every season of the Slovenian PrvaLiga since its formation in 1991. Celje won their first league title in the 2019–20 season. They have also won the 2004–05 edition of the Slovenian Cup.
The club was formed in 1919 as SK Celje. Soon after World War II, in 1946, the club changed its name to NK Kladivar (expressionistic term in Slovene for a blacksmith). In 1964 they qualified for the Yugoslav Second League, where they played for one year.
In 1992, one year after Slovenia gained independence from Yugoslavia, the club was renamed as Publikum due to sponsorship reasons. They reached the finals of Slovenian Cup in 1993 and 1995, but lost on both occasions, having been beaten by Olimpija and Mura, respectively. In 2003, Celje was in a title race with Maribor until the last two rounds, but in the end finished second and also lost the Slovenian cup final against Olimpija during the same season. Two years later, in 2005, the club reached the final for the fourth time and this time they finally lifted their first trophy, defeating Gorica 1–0 in front of their own fans at the Arena Petrol. Celje were also in the finals the next year, but lost to Koper after a penalty shoot-out. In early 2007, they dropped Publikum from their name.
In 2020, Celje won its first Slovenian league title after winning the 2019–20 Slovenian PrvaLiga season.