The two clubs both used their home-court advantage to win their respective quarter-final play-off series 2-1.
Pinar Karsiyaka prevailed 85-69 against Paris Levallois behind 22 points apiece by Robert Dixon and William Thomas, while Oldenburg recorded a convincing 100-78 victory against BC Khimik to reach their first EuroChallenge Final Four.
The two teams will play each other in the Semi-Finals, while Krasnye Krylia will take on BCM Gravelines.
Krasnye Krylia and BCM Gravelines had already clinched a spot in the Final Four by sweeping their quarter-final play-offs series 2-0 against Telekom Baskets Bonn and Joensuun Kataja respectively.
The Final Four, which will take place on 26 and 28 April 2013, will be hosted by one of the participating clubs. All clubs can submit their bid to host the event by the end of this week.
EuroChallenge Final Four 2013 Semi-Finals pairings:
Pinar Karsiyaka (TUR) vs. EWE Baskets Oldenburg (GER)
BCM Gravelines-Dunkerque (FRA) vs. Krasnye Krylia (RUS)