Jean Marie Muhirwa was born in Burundi, and belongs to the Hutu ethnic group.
He studied and lived in Kenya, and also spent time in Tanzania.
From 1994 he was a member of the ruling party, CNDD-FDD.
He became Administrator of the Bwambarangwe Commune of Kirundo, a province in the north of Burundi.
He was elected to the Senate of Burundi in 2015.
On 13 July 2016 Hafsa Mossi, Burundi representative in the East African Legislative Assembly (EALA), was assassinated in Bujumbura.
Jean Marie Muhirwa was elected to replace her in the EALA, gaining 103 out of the 109 votes cast in the Burundi National Assembly.
His tenure would end in June 2017.
On 11 August 2016 the Constitutional Court of Burundi declared that Muhirwa's senate seat was vacant due to his resignation.
Muhirwa was reelected for the 4th Assembly of the EALA to serve from 18 December 2017 to 18 December 2022.
Due to growing tensions between Burundi and Rwanda, in March 2017 the five Burundi MPs were visibly absent when President Paul Kagame of Rwanda addressed the EALA session in Kigali. In January they had warned the EALA speaker they would not attend because they were concerned about their safety in Kigali. The Burundi government had accused Rwanda of supporting armed groups who were planning to overthrow the government of President Pierre Nkurunziza.
In June 2020 Muhirwa was elected by the EALA as one of the two commissioners for Burundi, replacing Leontine Nzeyimana, to serve in the Assembly for the next two and a half years.
In October 2022 the National Assembly of Burundi elected Anastase Manirambona, national secretary of the CNDD-FDD, to replace Murirwa, who had recently resigned as MP of the EALA.
In February 2024 Muhirwa was National Secretary of the CNDD FDD party in charge of political and legal issues, and also godfather of Mwaro Province.
He participated in a ceremony in the Nyamiyaga colline in the Commune of Rusaka to launch construction of a classroom.