Tin Kai-Man, a Hong Kong actor and production manager, confirmed Law's death, saying his girlfriend Mabel Cheung Yuen-tin was with him when he passed away.

It was understood that Law had heart problems and has been seeing Chinese doctors in recent years. Due to a sudden heart attack, Law felt sick at home at dusk on Saturday and passed away in the ambulance to the hospital.

He was seen attending the premiere of the Korean movie Broker with Chueng at Premiere Elements on June 16, and taking photos with Chueng with a big smile on his face. It was also the last public occasion he attended.

Law graduated from the Diocesan Boys' School. His death first spread within the circle of Diocesan Boys' School's former students.

His friend Canon George Zimmern posted on social media on Sunday, "Director Law Kai-Yui, a former student in 1971 who has been the editor of the school magazine during his studies, was known for films including An Autumn's Tale, Now You See Love, Now You Don't and Echoes of the Rainbow... I just heard he had passed away. My condolences to his family, teachers, and friends."

Law and girlfriend Cheung were known for alternating as director and producer in the production of many classic and popular films.

He won the Hong Kong Film Award for Best Screenplay for "An Autumn's Tale" in 1987, as well as the Golden Horse Award for Best Original Screenplay for "Painted Faces" in 1988 and "City of Glass" in 1998.

In 2010, his "Echoes of the Rainbow" won the Crystal Bear for the Best Feature Film in the Generation section of the 60th Berlinale 2010.