The side's 1-1 draw at home to Hansa Rostock on Matchday 37 in Germany's third tier was enough to secure the south-western side promotion once more.
The visitors went ahead in the first half through Dutch striker Johan Plat, but defender Dennis Kempe levelled in the 74th minute to hand his team the point needed for promotion.
With one round of games still to play, Karlsruhe lead the standings on 76 points, having won 22, drawn ten and lost five of their fixtures this season. Third placed 1. FC Heidenheim are five points further behind in the play-off spot.