She was the gold medallist in that event at the 1967 European Indoor Games, having been runner-up to Zsuzsa SzabĂł the previous year at the 1966 European Indoor Games.
Kessler also represented her country at the 1966 European Athletics Championships, reaching the semi-finals.
She set a personal best of 2:03.6 minutes in 1967, which was a West German record for the Hamburg-born athlete.
Kessler was a five-time national champion individually, taking both indoor and outdoor 800 m titles in 1966 and 1967, as well as a short course cross country title in 1966.
During her career she was a member of DĂĽsseldorfer SV 04 and LG Alstertal / Garstedt Hamburg clubs.