[3] Onzima was born in Maracha District, West Nile sub-region, Northern Region on 26 June 1952.

He attended local schools before he entered Makerere University, where he studied public health dentistry from 2002 until graduating in 2005 with a Bachelor of Science.

In 2010, he formally left FDC and joined the ruling National Resistance Movement.

[6] In the cabinet created after the 2011 national elections, Onzima was appointed Minister of State for Local Government.

[7] In the cabinet list released on 6 June 2016, he was named State Minister in the Office of the Vice President.