Cheong Jun Hoong was born in Ipoh, Perak. She is the daughter of Cheong Sun Meng and Leow Lai Kuan.[5] She has a younger sister. Her fascination in aquatics began at the age of four. At age nine, she started her training in diving with Perak's state coach, Zhou Xiyang. In 2004, she was offered a place at the Bukit Jalil Sports School. She graduated with a bachelor's degree in Communications from Universiti Putra Malaysia.
In June 2017, Cheong returned from a back injury to win the bronze medal in the 1m springboard event at the 7th Asian Diving Cup in Macau after withdrawing from the Kazan and Windsor legs of the 2017 FINA Diving World Series earlier.[8] Cheong became Malaysia's first diving World Champion, when she took home the gold medal in the 10m platform event in the 2017 World Aquatics Championships in Budapest, pipping her closest rival by just 1.5 points.[9] Four of the seven judges gave a perfect 10 on her best dive in the competition, and she finished with an overall score of 397.5.[4] She also won a bronze in the 10m synchronized 10 platform event with Pandelela Rinong with a total score of 328.74.
Cheong was chosen as one of the flag-bearers for Malaysia at the 2017 Southeast Asian Games alongside two reigning world champions cyclist Azizulhasni Awang and silat exponent Mohd Al-Jufferi Jamari.
Retirement
On 4 January 2022, Cheong announced her retirement after her contract as a full-time athlete with the National Sports Council and Malaysia Swimming was not renewed.[2] One of the reasons Cheong provided for her retirement was a second knee injury she acquired in 2018 and had not been able to re-achieve a certain level of performance since then.[10]