Kalenberg began her career in 2001, after hearing about a casting on the radio. She appeared in two television films, Hanna – Where Are You? (Hanna – Wo bist Du?) in 2001, and In the End the Truth (Am Ende die Wahrheit) in 2002. In 2003, apart from appearing in television series Vice Squad (Die Sitte) and Tatort (Tatort), Kalenberg also made her film debut, in drama The Puppet Grave Digger (Der Puppengräber). Throughout 2004 and 2005, she acted in four television films — The Doctor (Die Ärztin), The Sting of Scorpion (Der Stich des Skorpion), Secret of the Red House (Das Geheimnis des roten Hauses) and Intrigue and Love (Kabale und Liebe). In Intrigue and Love, Kalenberg starred as Luise Miller, opposite famous German actor August Diehl.