[4] On 15 May 2012, he was named bishop of the Diocese of San Jose Nueva Ecija by Pope Benedict XVI,[1] and was installed on 10 July 2012.

[8] From 2015 to 2021, Mallari served as the chairman of the CBCP's Episcopal Commission on Catechesis and Catholic Education (ECCCE).

[14] In October 2019, Mallari rejected the idea that separating girls and boys in schools will lower the teenage pregnancy and HIV infection in the country.

This after the National Youth Commission earlier proposed to have separated rooms for boys and girls in schools to curb the said health issues.

[18]The rite of his canonical possession-installation will be held at the Tarlac Cathedral on March 27, 2025, to be presided over Apostolic Nuncio Charles John Brown.