Through his organization Behind Bar Human Rights Foundation,[6][7] he has worked to highlight the harsh conditions faced by prisoners in Nigerian jails and to provide assistance in securing justice for individuals who have been wrongfully imprisoned.
[13][14][15] Harrison Gwamnishu entered politics as a candidate for the Labour Party during the 2023 Delta State House of Assembly elections, representing the Aniocha South Constituency.
[26][27] In February 2024, Harrison accused officers from the Force Criminal Investigation Department (FCID) of extorting ₦3.15 million from a resident in Auchi, Edo State.
[28][29] In July 2024, Harrison Gwamnishu publicly criticized Nigerian police spokesperson ACP Olumuyiwa Adejobi for remarks concerning the death of Erasmus Emeya, a 33-year-old detainee.
[30] On 24 October 2024, the University of Nigeria Nsukka (UNN),[31] issued a statement demanding an immediate retraction and apology from Harrison Gwamnishu for allegedly defamatory remarks about the institution.
[32] The controversy arose after Gwamnishu shared a viral video online, claiming that a student had been beaten to death by unknown assailants on the university's premises.