Lucas Reiber was born 1993 in Berlin. He made his stage debut at the age of ten at the Theater des Westens in Berlin, as street boy Gavroche in the musical "Les Misérables". In 2008 he joined the "junge Ensemble" (jE) of the Friedrichstadtpalast, where he studied singing and acting until 2011; he also took dance lessons there.

During this training Reiber played his first screen role in 2009, in the two-part television film "Ken Folletts Eisfieber" (Director: Peter Keglevic), as grandson of Heiner Lauterbach's main character. The following year he was seen in his first feature film on the big screen, the youth film "Rock It!" (2010), as keyboarder of the titular rock band. In "Einer wie Bruno" ("Someone Like Him", 2011) he also played a young musician and pupil, with whom the daughter of Christian Ulmen's title character falls in love.

Reiber played his first leading role in the TV movie "Sprung ins Leben" (2014), as a talented football player who is in a wheelchair after a car accident. In the historical TV two-parter "Die Himmelsleiter - Sehnsucht nach morgen" (2015) he played the son of Axel Prahl's main character. Reiber had an important leading role in "Die Mutter des Mörders" ("The Mother of the Murderer", 2015), as the mentally handicapped son of a supermarket saleswoman suspected of murder. He received the New Faces Award for his performance in this film. In the same year he had the supporting role of the autistic Etienne, nick-named Ploppi, in the comedy hit "Fack ju Göhte 2" ("Suck Me Shakespeer 2", 2015). Together with Anna Lena Klenke, Gizem Emre, Max von der Groeben, Aram Arami and Jella Haase he was awarded the Bavarian Film Prize for his performance.

Among his further appearances on the big screen are a womanizer in the comedy "Verrückt nach Fixi" (2016) and a riding instructor in "Hanni & Nanni: Mehr als beste Freunde" (2017). For "Fack ju Göhte 2" (2017) he reprised the role of the autistic Ploppi. Also in 2017 he belonged in a supporting role to the ensemble of the documentary drama "Die Unsichtbaren - Wir wollen leben" ("The Invisibles"), about a number of young Jews hiding in Berlin during the Nazi era. In addition, Reiber continued to play guest roles in various series, such as in several episodes of "Binny und der Geist" ("Binny and the Ghost", 2014-2016) and "Club der roten Bänder" ("The Red Band Society", 2016), as well as in episodes of "Der Kriminalist" (2017) and "Katie Fforde" (2017).

Lucas Reiber had a new leading role in the comedy "Abikalypse" (2019), as one of four school outsiders who want to prove themselves to their classmates by means of throwing a gigantic graduation party.