[2] He had his early education in Tuaran (he was only born there but brought up in his hometown of Putatan in the Penampang district, where both his parents are originally from as either his father or mother was stationed in the above district due to a job post with the colonial government) which caused his mother to give birth to him in that district, what more spending his partial childhood and teenage years before completing his secondary education at La Salle Secondary School, Kota Kinabalu.

He was also admitted to the English Bar of the Honourable Society of Gray's Inn in London.

Upon his return to Malaysia, Malanjum continued his service as deputy public prosecutor and senior legal counsel at the Sabah State Attorney-General's Chambers.

[8] On 28 January 2022, he was appointed by the Secretary-General as the Ombudsperson of the United Nation's Security Council.

Called a “fearless and staunch defender of the integrity of the Federal Constitution and fundamental liberties” by Retired Court of Appeal judge Datuk Hishamudin Yunus for his dissenting judgements whilst in Federal Court, Richard was claimed to have made 'brave' judgements in the controversial cases of Lina Joy (2007) in which he had adjudge the insistence by the National Registration Department for a certificate of apostasy from the Federal Territory Syariah Court was not only unlawful but also unreasonable, The Herald/Allah Case (2014) “According to Justice Richard Malanjum, there were merits in the applicant's contention that the Minister's decision contravened Article 11(1) and (3) of the Federal Constitution, and therefore leave to appeal to the Federal Court ought to be granted (whereas in this case leave to appeal to the Federal Court was refused by the Federal Court).”Richard had also made separate judgements in other cases including Public Prosecutor vs Koh Wah Kuan (2007), Sivarasa Rasiah vs Badan Peguam Malaysia (2010), M. Indira Gandhi vs Pengarah Jabatan Agama Islam Perak and others (2018) and Alma Nudo Atenza v Public Prosecutor (The double presumption case) (2019).