[3][12] While residing in Quezon City, he studied at San Beda College from primary level until he finished Bachelor of Laws.

[13] In 1987, ran under the local political party Bagong Lakas ng Nueva Ecija (Balane), he was elected representative of the province's first district,[7][6][5] serving in the 8th Congress until 1992.

[13] Originally seeking for return as district representative,[14] he replaced his elder brother, Tomas III, ran (Balane–Laban ng Demokratikong Pilipino–Nationalist People's Coalition) and was later elected provincial governor[15][6][5] against Virginia Custodio–Perez (of then ruling Lakas–NUCD), who replaced her husband, Cabanatuan mayor Honorato Perez, killed few weeks prior to the 1995 elections in which Tomas III and then Quezon mayor Mariano Cristino were implicated.

[16] Eduardo Nonato served until 1998[3] as Tomas regained the governorship in that year's elections while in detention; the cases against all the accused were eventually dismissed.

[19][20][18] On January 8, 1998, he was found guilty of the offenses and a six-month suspension was imposed, which he defied as the provincial capitol compound was cordoned off until the authorities hastily and peacefully retreat;[4] the Supreme Court in May declared the said order null and void.

He initiated seedling and fertilizer subsidy to farmers; establishment of post-harvest facilities and equipment; and introduced electronic system of trading in agriculture.

[12][27] Edno, ran under PDP–Laban, lost to his younger brother and re-electionist mayor of Quezon, Mariano Cristino (Boyet), in the 2022 elections.

The petition claimed that he is a Guimba resident since 2000, and has long abandoned his place of birth as he had never owned a property there, citing affidavit issued by their mother and other documents.

[6] In January 2022, the Commission on Elections First Division granted the said petition;[29] ruling that there are insufficient information to establish that he is able to comply with the residency requirement.