In his youth he was a leather merchant. Abromeit joined the Nazi Party (member number 329,305) and the SS (member number 272,353). In 1937 he became an SS-Untersturmführer, in 1938 SS-Obersturmführer and in 1940 SS-Hauptsturmführer. From 1939 to 1941 as served as head of the SD-Special Section for the Evacuation of Poles and Jews that forced resettlement from Danzig and West Prussia.
From 1942 he was Jewish adviser to Croatia in the Jewish Section (IVB4) of the RSHA with SS Lieutenant Colonel Adolf Eichmann. 5500 Jews were deported and murdered mostly. In 1944 he was employed with Eichmann, Dieter Wisliceny, Theodor Dannecker, Hermann Krumey, Siegfried Seidl, and Franz Novak in Hungary, to overlook the deportation of Jews in the concentration camps at Auschwitz. Over 430,000 Jews were deported from Hungary, of whom some 200,000 were exterminated upon arrival. Abromeit was one of the closest stewards under Eichmann.
He escaped Germany as World War II came to an end and was believed to have gone to Egypt. In 1964 he was declared dead and had long been untraceable.