During the tenure of President Diosdado Macapagal, he was named part of a 12-member select committee which was tasked to draft and pass the first Land Reform Code of the Philippines.

[5] Cojuangco became the campaign manager for the LABAN party which was led by then Senator Benigno Aquino Jr. for the Philippine parliamentary elections in 1978.

After the controversial election, he joined as a leader of the side that called for President Ferdinand Marcos' ouster at the 1986 People Power Revolution.

At the 9th Congress he served as chairman of the Special Committee on Food Security and authored the Agrarian Reform Communities Act as part of the agriculture body.

[5] Cojuangco also became the founding chairman of Kampi which was originally organized in 1997 to support the presidential bid of then Senator Gloria Macapagal Arroyo in the 1998 Philippine elections.

Arroyo then later settled to run for vice president instead after Kampi formed a coalition with Lakas–NUCD which had Jose de Venecia Jr. as its standard bearer.

[6] Cojuangco remains affiliated with Kampi which continues to exist until 2008 and has his wife as its chairperson in support of then President Gloria Macapagal Arroyo.

Cojuangco campaigned that he would secure funds from the private sector saying that the effort won't be hard as long as "businessmen know that the money they’re donating are being used properly".

[11] However, the 2016 election was nullified by the Pasig Regional Trial Court after a petition from ABAP president Ricky Vargas was granted.

A new election was held on February 23, which was subsequently won by Vargas, ending Cojuangco's 13 year team as POC president.

[15] He is married to Margarita "TingTing" de los Reyes, President of the Philippine Public Safety College and former Governor of Tarlac.