Originally from Yanggu, Gangwon, Cheong graduated from the Seoul National University College of Law and 17th class of the Judicial Research and Training Institute before beginning his career as a judge for the Seongnam Branch of the Suwon District Court [ko] in 1988.

[1] Upon graduation from the Judicial Research and Training Institute, Cheong was hired as a judge for the Seongnam Branch of the Suwon District Court [ko] in March 1988.

[7] Chief Judge Cheong ruled in Jeong Yeon-ju's favor, finding President Lee's dismissal was an illegal abuse of discretion.

[8] In a retrial held by the Seoul High Court on July 31, 2013, Cheong ruled Sungkonghoe University professor Cho Hee-yeon [ko] was not guilty of violating Emergency Measure No.

[6][9] In 1978, Cho, who was then a student at Seoul National University, was indicted for creating and distributing leaflets that criticized the Yushin Constitution and sentenced to two years in prison.

[9] In finding Cho not guilty, Cheong noted the emergency measures were unconstitutional because "it is clear that they were intended to suppress the people's resistance to the Yushin regime.

[12] During the appeal trial, Cheong disagreed with the first court's finding and found Han Man-ho's initial statement to the prosecution to be credible.

[11] In imposing a sentence of two years in prison and fine of 883 million won, Cheong stated the nature of crime of was serious and that Han Myeong-sook lacked remorse.

[14] The initial five-year sentence had been imposed by the Seoul Central District Court after they convicted Lee of perjury, embezzlement, and bribery in August 2017.

[16] In reducing Lee's sentence, Cheong overturned the district court's rulings on some of the bribery charges and stated "it is difficult to acknowledge that there was a comprehensive issue of Samsung's succession process.

[22] Cheong also was questioned about making six million won in donations to a North Korean defector support group from 2018 to 2022 that had conservative leanings.

"[22] On December 18, 2023, the National Assembly's Legislation and Judiciary Committee adopted a personnel hearing report that contained split opinions on whether Cheong was qualified for appointment to the Constitutional Court.

[26] On the same day, Cheong received his official letter of appointment from President Yoon and attended an inauguration ceremony at the Constitutional Court on December 19, 2023.

[32] On February 28, 2024, Cheong was part of a 6–3 majority of the Constitutional Court that held the Medical Act's ban on revealing the sex of a fetus until the 32nd week of pregnancy was unconstitutional.

[33] The court held restricting gender disclosure was no longer reasonable as the preference for male children has declined as evidenced by South Korea's sex ratio at birth reaching the normal range in 2014.

[34] On August 29, 2024, Cheong joined a unanimous majority of the Constitutional Court in ruling the Carbon Neutrality Framework Act's failure to set a greenhouse gas emissions reduction target after 2031 was unconstitutional because it failed to protect basic rights.

[35] Cheong is married to the youngest sister of Park Seon-yeong [ko],[36] the current chairwoman of the Truth and Reconciliation Commission,[37] and has two sons.