In 1937, he was engaged at the North-Land Mark Theater in Schleswig, where he made his debut in Ferdinand's tragedy Egmont, by Johann Wolfgang von Goethe.
Jaeger played the role of the actuary Faber in the notorious Nazi propaganda film Jud Süß (1940) which was directed by Veit Harlan.
In 1960 he starred in the successful TV miniseries Am grünen Strand der Spree, based on the book by Hans Scholz, In 1967, he played Hans-Joachim Lepsius, one of the main characters in The Reichstag fire trial or in Sand in 1971.
He was also in several TV series such as occurred in Die fünfte Kolonne [de], Timm Thaler, Schwarz Rot Gold and Das Erbe der Guldenburgs.
As a voice actor, he was dubbed over Montgomery Clift in A Place in the Sun and Guy Decomble in Can't anyone love you...?.
In the early sixties, he met his future life partner, Elly Philomena Mary Wolf, with whom he cohabited for 30 years until his death on 10 January 1991.