Kiefer started acting at ITS DNA (Preliminary Theater Training School) and studied at the Theater School ArtEZ in Arnhem.
He has starred in a number of notable plays, including Ibuca from Theater Utrecht, Watskeburt?! The Musical from Bostheater Productions, Showponies I & II, a theatershow by Alex Klaasen, and several plays from theater group DOX.
Kiefer has also starred in films such as Thuisfront (2021), De Zitting (2021), and tv series such as Dokter Roman (2021), Goede Tijden, Slechte Tijden (2021-2022), NOOD II (2023), and Santos (2023)
More recent features with Kiefer are Dit is geen kerstfilm, Rokjesnacht, the series Suga, Ride or Die and the film Een best wel heftige date
