Muhammad Mustafa began his journey to the legal profession upon enrolling in the Faculty of Law of Universiti Teknologi Mara (UiTM) for his Bachelor of Legal Studies Degree program and Bachelor of Law (Hons) Degree Program as a Jabatan Perkhidmatan Awam (JPA) scholar.

He obtained his first degree, the Bachelor of Legal Studies with distinction Second Class Upper in the year 2013 and subsequently continued his studies and obtained his second degree, the Bachelors of Law (Hons) also with distinction Second Upper Class in the year 2014.

He then commenced his pupillage in the chambers of Farah Shireen binti Mohammed Said at Messrs. Zul Rafique & Partners in November 2014. There, he was placed in the Corporate Energy & Utilities Department, specifically the Oil & Gas Department.

He was later admitted as an Advocate & Solicitor of the High Court of Malaya on the 30th of October 2015. Shortly after being admitted to the Bar, he joined Messrs. Sulaiman, Jamellah & Clement in 2015 as a partner and co-established a new firm, known as MARCO.