His research focuses on the detection of cell-free fetal DNA in blood plasma,[5] and he is best known for his contributions to the development of non-invasive prenatal testing At CUHK, Lo is also the Associate Dean (Research) and Li Ka Shing Professor of Medicine at Faculty of Medicine, the head of the department of chemical pathology, and the director of the Li Ka Shing Institute of Health Sciences.

[4] His mother taught music and his father, Lo Wai-hoi,[6] who immigrated from Chaozhou to Hong Kong in 1946,[7][8] was a psychiatrist and the former head of Castle Peak Hospital.

[7] In 1983, at the age of 20, Lo arrived at Cambridge, where he spent two years completing his preclinical medical training and a BA degree, and his third studying genetic cloning.

[clarification needed][7][8] Lo completed his medical degree (BM BCh) in 1989; he was at Christ Church College during this period.

[3] Lo began his research career studying polymerase chain reaction (PCR), a molecular biological technique for rapidly generating millions of copies of a desired DNA sequence.

[7][8][13] Working with Kenneth Anthony Fleming, his future PhD advisor, Lo found the relatively new technique generated a lot of false positives due to contamination.

[16][17] In 1997, again using the Y chromosome as a marker in mothers bearing baby boys, Lo reported the presence of cell-free fetal DNA in most of the test subjects.

[7] Lo, who by the time was married, returned to Hong Kong the same year with his wife, as the city was preparing its handing back to China.

He became a senior lecturer in the Department of Chemical Pathology at the Chinese University of Hong Kong (CUHK) in January 1997.

"[19] One of the first disorders for which Lo developed non-invasive prenatal testing using cell-free fetal DNA was Rh disease, a type of anaemia that occurs when the foetus is Rh-positive but the mother is Rh-negative.

[27] When used to detect Down syndrome, which is caused by an extra chromosome 21, this method was later shown to have a 100% sensitivity and a nearly 98% specificity,[28] prompting its introduction into clinics in 2011.

[63] It was reported in 2021 that Lo bought a flat at The Masterpiece in Tsim Sha Tsui, Hong Kong for HKD$210 million.