Allach studied social pedagogy after high school. He started his professional career at a relatively late age. He was a youth worker in Gouda, South Holland and played at amateur level with DWO in Zoetermeer and Alphense Boys when he was recruited in 1996 by the second-tier Eerste Divisie club Excelsior.[2][3] Halfway through the 1999–2000 season, Allach moved to top-tier side Feyenoord, where he did not make an official appearance.[4] In 2000, he left for Groningen, where he was a regular starter for more than two seasons.[5] In 2002, he was forced to leave there after a conflict with head coach Dwight Lodeweges, who called him a "source of friction" in the squad.[6]
Allach then played for Dordrecht in the Eerste Divisie and Twente in the Eredivisie. When he was unable to enforce a regular starting spot at the last club, he left for VVV-Venlo in 2004. In 2006, he retired from professional football and then started working as technical director and head of practice at VVV.[7]
In 2008, Allach moved from the role as technical director and head youth academy of VVV to FC Twente, where he became director of football.[8] After one season at Twente he became director of football affairs at RKC Waalwijk.[9]
In July 2013, Vitesse announced that they had contracted Allach as technical director. He succeeded Ted van Leeuwen.[12] Allach held that position until 2017. During this period, Vitesse won the KNVB Cup, the first silverware in club history.[13] After a short stint with Israeli club Maccabi Haifa,[14][15] Allach returned to Vitesse in March 2019. [13]Allach left the club nine months later after a conflict with club management.[16][17]
In late 2003, Allach and friends founded the Maroquistars Foundation, a volunteer organisation that aims at strengthening young people in terms of social resilience through social projects.[19]
^"Woensdagnieuwtjes". Alphense Boys (in Dutch). 5 March 2019. Retrieved 13 February 2021. Mohamed Allach (speelde in 1994 in Alphense Boys 1 en ging daarna naar Feyenoord) keert terug als technisch directeur bij Vitesse.
^"Mohammed Allach (1973)" (in Dutch). Kent U Deze Nog?. 24 January 2013. Retrieved 13 February 2021.
^"Folder Maroquistars"(PDF) (in Dutch). Stichting Maroquistars. Retrieved 13 February 2021. Stichting MaroquiStars is in 2003 opgericht op initiatief van oud profvoetballer Mohammed Allach. Stichting MaroquiStars richt zich tot kwetsbare groepen in de Nederlandse samenleving zijn, waarover een negatieve beeldvorming is ontstaan.