Schmorell's father was Hugo Schmorell a medical doctor, was German-born and raised in Russia. Schmorell's mother was Natalia Vedenskaya a Russian, the daughter of a Russian Orthodox priest. Schmorell was baptised in the Russian Orthodox Church. His mother died of typhus during the Russian Civil War when he was two years old. In 1920 his widowed father married a German woman, Elisabeth Hoffman, who, like him, grew up in Russia. They left Russia and moved to Munich, Germany, in 1921, when Schmorell was four years old. His Russian nanny, Feodosiya Lapschina, came along with them and she took his late mother's place in his upbringing. Alexander Schmorell grew up bilingual, speaking both German and Russian. His friends gave him the nickname 'Schurik', a nickname he would be called by his closer friends for the rest of his life. He was an Eastern Orthodox Christian who considered himself both German and Russian.
After his Abitur (equivalent to high level High School diploma), he was called into the Reich Labour Service (Reichsarbeitsdienst) and then into the Wehrmacht (German Army during the Nazi era). In 1938, he took part in the annexation of Austria and eventually in the Wehrmacht invasion of Czechoslovakia.
After his military service, the artistically gifted Alexander Schmorell began studies in medicine in 1939 in Hamburg. In the autumn of 1940, he went back with his student corps to Munich where he got to know Hans Scholl, and later Willi Graf. Together with Hans Scholl, Schmorell put together the White Rose's first four anti-Nazi leaflets. In the second leaflet Schmorell wrote a passage containing an outcry against the Holocaust.
In June 1942, Schmorell took part as a combat medic in the Russian campaign on the Eastern Front, together with Hans Scholl, Willi Graf and Jürgen Wittenstein, and came to strongly oppose the Nazis' treatment of enemy soldiers and civilians during campaigns there. Once back from Russia, he continued his studies in Munich in the 1942-1943 semester.
In December 1942, Schmorell, along with Hans Scholl, sought contact with Professor Kurt Huber. Together in 1943 they wrote the fifth leaflet "Aufruf an alle Deutschen!" (Appeal to all Germans!), which Schmorell then distributed in Austrian cities. Along with Hans Scholl and Willi Graf, he also painted words such as "Nieder mit Hitler" (Down with Hitler) and "Freiheit" (Freedom) on house walls in Munich. It is suggested that he and Sophie Scholl, (Hans' sister) shared a romance, although Sophie herself was previously engaged to Fritz Hartnagel. However, little evidence of this exists outside of Lillian Groag's play The White Rose.
After the arrests of Christoph Probst and Hans and Sophie Scholl, Schmorell attempted to escape to Switzerland but was eventually arrested on 24 February 1943, the day of his friends' funeral, after being recognized in an air raid shelter.
Alexander Schmorell was sentenced to death on 19 April 1943 at the Volksgerichtshof (People's Court) in the second trial against the White Rose. In the letters he wrote from prison he tried to console his family and assured them that he was at peace with his fate and not fearful of death. On 13 July 1943, at the age of 25, Schmorell was put to death by guillotine along with Kurt Huber at the Munich-Stadelheim Prison.
Completing the act of canonization, Alexander was glorified as a saint and Passion bearer by the Russian Orthodox Church Outside Russia in Munich, Germany on February 5, 2012.
Schmorell was portrayed by Johannes Suhm in the film Sophie Scholl: The Final Days.