Chung became a Politician when he was elected as an assembly man in 1988 and served consecutive 7 terms in two different electoral districts. Initially he was elected in Dong District, Ulsan where predominant share of its population consisted of Hyundai heavy Industries Group's employees, its affiliated companies' employees, and their families. Most of other population in Dong District run businesses related with serving those workers and their families. Chung served as a representative of this particular district for 20 years. He joined Grand National Party in 2007 shortly before 2007 South Korean presidential election, declaring his support to that party's presidential candidate Lee Myung-bak. As a member of Grand National Party, he switched his electoral district to Dongjak District, Seoul, and represented there as an assembly man for 2 terms until 2014 when he had to give up that seat to run for mayor of Seoul, but the election was lost to Park Won-soon leaving no political titles for Chung after. Grand National Party changed its name to Saenuri Party in 2012. Chung had announced his candidacy for FIFA President. However he has been banned from all football activities for six years by FIFA Ethics Committee in October 2015.

Chung's real mother is unknown. When he ran for the South Korean presidency in 2002, Grand National Party explored on this point. They pondered various speculations about the identity of Chung's real mother. They speculated that his real mother could be a house maid, a geisha, or a particular traditional musician whom Chung Ju-yung had an affair with. In fact in his interview with news reporters in 2002, Chung indicated that his real mother is someone else, saying he would say truth someday. It was reported that he was crying sorrow when he was questioned about his real mother. Chung explained about his real mother in his autobiography in 2011. Chung says that when he studied in US in 1978, he received a letter from someone in Korea who claimed to be his real mother. He hurried to return to Korea, and met her at her place, according to his autobiography. Chung says this was the first and last for him to see that woman.

Chung's brother Chung Mong-hun, then the President of Hyundai Asan who pioneered South and North joint Mount Kumgang tour Business, committed suicide on Aug 4, 2003 when he was investigated by prosecutors for his alleged $400 millions cash remit to North Korea shortly before 2000 North-South summit. Initially this suspicion was raised from US when Congressional Research Service reported such allegation from CIA source on March 5, 2002. Upon hearing of such report, Grand National Party made use of this suspicion to attack the legitimacy of President Kim Dae-jung's government, and demanded thorough investigation through hearings and independent special prosecutors. Several weeks before leaving his office, President Kim gave an apology and advised no investigation for this matter for fear of aggravating North and South's relation, and Chung Mong-hun also confessed much of the allegations to public in his final attempt to evade investigation. But Grand National Party was resolute in its demand for formal investigation. Shortly after Roh's inauguration, Grand National Party passed the law entitling special prosecutors to investigate this case, taking advantage of its majority seats in National Assembly. Roh's regime wasn't able to refuse the demand of investigation, and Chung Mong-hun committed suicide when he was investigated about the use of $15 millions worth of Korean won which was suspected to had been money laundered after its withdrawal from Hyundai's bank accounts. In fact, the money wasn't part of $400 millions cash remittance to North Korea. North Korea blamed Grand National Party immediately after Chung Mong-hun's suicide. So Chung Mong-joon has joined the party which could be considered to be responsible for his brother's death, but Chung blames President Roh instead. In his autobiography which was published in 2011, Chung argues that President Roh didn't refuse Grand National Party's demand of investigation because he believes Roh actually wanted to investigate his brother to revenge on his withdrawal of supporting Roh in 2002 presidential election.

Chung is losing popular support in South Korean politics now. When he ran for assembly man in 2008, he received 54.41% of votes in Dongjak District, but for the following election in 2012, he just received 50.80% barely surviving to lose to the opposition candidate. When he ran for mayor of Seoul in 2014, he received 43.03% votes from Seoul residents losing to then incumbent mayor of Seoul and previous civil rights Activist Park Won-soon who received 55% of total votes. It turned out that Chung's electoral district, Dongjak voted only 41.80% for Chung whereas it gave 57.45% for Park's favor.

On top of publishing autobiography, Chung also donated huge money and set up a charity foundation in 2011, a year before 2012 presidential election. He contributed $200 millions worth of Korean won from selling approximately 5% of his assets and established Asan Sharing Foundation which offers educational opportunities and financial assistance to young people from low income families. He said he funded it to commemorate his late Father Chung Ju-yung, but many couldn't dismiss reasonable suspicion that his motivation was to impress public before presidential election. In fact Chung didn't deny such suspicion, arguing that donation is supposed to good regardless of purpose.

Chung didn't think of Park Geun-hye as accomplished as himself before 2012 presidential election. When he decided to compete with Park, he said he was a better choice as a presidential candidate because of his educational background and work experience. When he pointed out Park's disadvantage, he argued that expertise of politics and economy is not something to be achieved in a short time. When Park Geun-hye wrote an article about North Korean issue in Foreign Affairs, Chung discredited it claiming someone else had written it under her name. Therefore, it was clear that he wouldn't miss 2012 presidential election. In 2012, he ran for the presidency, but only briefly. He was the first Politician who submitted application for registration as a preliminary presidential candidate on May 1, 2012, but dropped out of the race in a couple of months. He wanted rule change for primary election so that general population choose party's presidential candidate, but he wasn't able to make this demand sound serious to Grand National Party, since Park Geun-hye's followers dominated and controlled the party. He gave up his candidacy and supported Park after. When he advertised Park at streets, he was saying to crowd that Park was prepared, and she was the one to take good care of economy and diplomacy.