Kerstin Fernström has appeared in about 45 film and television productions, including "Ein Bayer auf Rügen", "Frauenarzt Dr. Merthin", "Alphateam", "Zur Kasse bitte!", "Morden im Norden", "Anna und die Liebe", "Hubert ohne Staller", etc..  At a very early stage she played with Gerd Fröbe in the ZDF highlights "Frühling im Herbst" and "August der Starke", as well as with Lilli Palmer in "Eine sonderbare Dame".

The two short films "Allein mit Dir" (Alone with You) and "Glashaus" (Glass House), in which Kerstin played the leading roles, were awarded in 2019, 2020 and 2021. As well as the film "Seemingly Dead" in 2022.

Kerstin Fernström is at home on all comedy stages in Germany but she has also been on the road with many big touring leading roles, e.g. in " Ein Glas Wasser" / Scribe, "Die Probe oder die bestrafte Liebe"/ Anouilh, "Im besten Einvernehmen"/ Ayckbourn, "Die Heirat"/ Gogol, "Tief in der Nacht"/ Durbridge, "Rein oder raus" etc..

She has appeared on stage over 800 times in the leading role of "Fräulein Engel" in "Der Neurosenkavalier" with Claus Biederstaedt. And by the same author Gunther Beth as "Charlie" in " Die Katze" together with Karin Dor also several 100 times.   And she also played "Rose" in the German stage adaptation of "Golden Girls" about 300 times. 

With Family Theater Fernström, Kerstin was also the producer of her own one-woman shows for many years.

Another project is the collaboration with Sweden's biggest entertainment producers Lars and Krister Classon. 
Kerstin translated their comedy "Ungeheuer Heiss" into German and also holds the performing rights. The play had , despite Corona, its German premiere at the Theater an der Kö Düsseldorf. in late August 2020, then went on tour with the Komödie im Bayerischen Hof two, 20/ /21 and also played on the summer stage of the Komödie in Munich in 2021.