His interest and degree in architecture proved useful in rehabilitating and renewing the City of Manila, which had fallen to decay over years of unmanaged growth in population and the lack of an urban planning & community development.

Atienza was first elected as Member of Parliament in the then At-large Congressional District of Manila under the Batasang Pambansa in 1984 and served until Marcos was peacefully ousted during the People Power Revolution of 1986.

[5] The Supreme Court ruled on April 17, 2007, that Franklin Drilon was the real president of the Liberal Party and not Atienza and has approved the Daza-Drilon Amendments to the LP's Charter.

COMELEC earlier ruled that Drilon's term as LP president has already expired and called for the holding of elections to end the leadership vacuum in the country's oldest political party.

[6] On November 26, 2007, at Club Filipino, Greenhills, San Juan, LP National Executive Council officials resolved to appoint Senator Mar Roxas as president of the Liberal Party (Philippines).

[7] Atienza, however, questioned Roxas' appointment, attacking the composition of Liberal Party's National Executive Council (NECO) and alleged that the Supreme Court of the Philippines' June 5 resolution ordered the LP leadership's status quo maintenance.

[9] Atienza, a staunch supporter of President Gloria Macapagal Arroyo, was named Environment Secretary on July 18, 2007, replacing Angelo Reyes, who was moved to the Department of Energy after incumbent Raphael Lotilla resigned.

As Manila mayor, Atienza in 2003 enraged environmentalists when he ordered the closure of the Arroceros Forest Park to give way to the building of an education office and a teacher's dormitory, sparking a lawsuit.

The Kalikasan People's Network said that Atienza had no moral authority to be at the helm of the DENR because he had "neither had sterling qualifications nor a clean track record of protecting the environment as former Manila Mayor.

[11] Atienza underwent knee replacement surgery in February 2022 days after spraining his foot,[12] making him unable to join Pacquiao in his campaign sorties, as well as the vice presidential debates.

Public places such as the Plaza Miranda, the Andres Bonifacio monument, Rajah Sulayman, the Binondo areas, the creation of a Linear-Park in Pandacan, renovating Carriedo and the R. Hidalgo streets in Santa Cruz, upgrading services of the city's public libraries, schools and hospitals including the Ospital ng Maynila and the building a permanent campus for the Universidad de Manila are among the achievements under Atienza's administration.

Historians also questioned Atienza's respect for historical architecture when the mayor ordered the demolition of the Manila Jai Alai Building along Taft Avenue to give way to the envisioned Hall of Justice to house the city's regional trial courts.

The mayor battled the country's three major oil companies, the partly state-owned and Saudi Aramco managed Petron, Dutch-owned Pilipinas Shell and Caltex-Chevron.

Atienza had been severely criticized by cultural activists for his heavy-handed decision to demolish the famed Jai-Alai Building along Taft Avenue, designed by Hollywood architect Welton Beckett.

Barely days after Atienza stepped down from office, his successor, Mayor Alfredo Lim reversed several of the former's civil works projects such as the removal of the promenade along Rizal Avenue and the closure of the cafe and bars along the Roxas Boulevard Baywalk.

In a separate development, the former Vice-Mayor Danny Lacuna accused Atienza of selling out the property allocated for the Jose Abad Santos High School in the district of Binondo.

Atienza hosted the Philippine television drama romance anthology, Maynila, broadcast by GMA Network from December 13, 1999 (a year after he became Mayor of Manila) until its hiatus on August 1, 2020, due to the implementation of the modified enhanced community quarantine (MECQ) in Metro Manila amid the surge of COVID-19 cases in the region,[17] where sometimes he acted for some cameo role, who gives advice to the characters.

Atienza appeared in a series of advertisements alongside the Mayor of Townsville from The Powerpuff Girls (voiced by Tom Kenny) to promote the campaign.