Marku made his professional debut on 1 December 2018, scoring a first-round technical knockout (TKO) victory against Nikola Janicievic at the Beste Event Halle in Ulm, Germany.
[2] In November 2020, after compiling a record of 7–0 (5 KOs), he signed a promotional contract with Eddie Hearn's Matchroom Sport.
The bout served as part of the undercard for Anthony Joshua vs. Kubrat Pulev and was televised live on Sky Sports Box Office.
In a fight which saw Marku drop his opponent to the canvas with a punch to the body in the second round, the result was controversially announced as a draw, with referee Marcus McDonnell scoring the bout 76–76.
On 25 August, it was announced that the bout would now take place on 25 September at Tottenham Hotspur Stadium on the undercard of Anthony Joshua vs. Oleksandr Usyk which he won via split decision after 10 rounds against Maxim Prodan.