Aingimea studied law in Australia and subsequently worked for the Regional Rights Resource Team NGO, and as a public defender in the Marshall Islands. He later worked as a lecturer in law at the University of the South Pacific.
Aingimea ran for election to Parliament in the Meneng Constituency in 2013, but failed to be elected. Following the elections, he joined the new administration of President Baron Waqa as Secretary for Justice.
After successfully contesting the Meneng seat in the 2016 elections, he was appointed Assistant Minister for Justice and Border Control in Waqa’s government, serving under Minister for Justice David Adeang. He was re-elected in the 2019 elections, which saw Waqa lose his seat. Following the elections, he was elected President by Parliament, defeating Adeang by twelve votes to six.