Mhagama is a politician belonging to the Chama Cha Mapinduzi party, and was previously a Member of Parliament for Peramiho constituency.

[2] Mhagama first became involved with CCM in 1987 and served in a variety of roles including in the youth and women wings of the party.

[2] In 2005, she defeated former Finance Minister Simon Mbilinyi in a primary for the right to represent CCM in the upcoming elections for Peramiho constituency.

[3] An analysis found that Mhagama was the second most active MP in the 2005-2010 Parliament in terms of contributions to debates and questions to ministers.

Mhagama was sworn in as Tanzania's Minister of Health on 15 August 2024 by President Samia Suluhu Hassan.