[2] After World War II, the club became part of a larger sports association and renamed as Aurora.

In the 2005–06 season, Mladen Rudonja returned to the club and brought with him the Serbian-American businessman Milan Mandarić, who paid off all the remaining debts.

After the first half of the season, before the arrival of the new patron, Koper was battling against relegation, but in the second part of the season, with a new coach, Milivoj Bračun, the club started an unbeaten run that led them to reach the third place in the Slovenian PrvaLiga and to win the Slovenian Cup for the first time.

In the 2009–10 season, the team was expanded and, under the leadership of veteran player Miran Pavlin, eventually won the Slovenian PrvaLiga championship for the first time,[4] securing a place in the UEFA Champions League qualifiers, where they were defeated by Dinamo Zagreb 5–4 on aggregate (1–5, 3–0).

Following the 2016–17 season, Koper failed to obtain a competition licence and was excluded from the Slovenian top division.

[10] Note: Flags indicate national team as defined under FIFA eligibility rules; some limited exceptions apply.