The musical director, who worked with many of the world's leading orchestras and choirs, passed away peacefully at his home on Monday.
His death was announced last night on the cathedral's Facebook page.
The post stated: "At his request, there will be no funeral service, but we will host a memorial service early in 2024.
"It is with great sadness that we advise of the death of our former Director of Music Brian Law.
"Brian ruled the Choir from 2003, when he was asked to ‘help out’ over Christmas.
"He forgot to stop helping and saw the Cathedral survive earthquakes and only retired after we had moved into the Transitional Cathedral in 2014.
"He remained a strong supporter of the Cathedral up to his death, critiquing services either in person or by watching live-streams!
"At least two full generations of Cathedral Choristers and a healthy number of back row of the Choir will remember him for his musical brilliance, his humour and, on occasions, “the look” that could wither anyone at 100 paces.
Law was born and educated in London. He emigrated to Canada when he was 22 and became music director of the Ottawa Symphony Orchestra, Ottawa Choral Society, and a founding director of the baroque ensemble Thirteen Strings.
For 14 years he was the organist and choirmaster at St Matthew’s Anglican Church in Ottawa, where "he brought the men’s and boys’ choir to a standard of excellence comparable to that of British collegiate and cathedral choirs".
Law conducted many big international orchestras during his career and worked in opera and ballet.
He conducted orchestras in the United States, Italy, Spain, Egypt and the UK. He appeared at international festivals such as Opera at the Pyramids in Egypt.
Law moved to Christchurch in 1990 and was a frequent guest conductor of the Christchurch Symphony and a founding director of Cantores.
"The city’s musical landscape expanded, heightened and developed enormously through his work with the City Choir, Canterbury Opera and Southern Opera, as frequent guest conductor of the Christchurch Symphony and founding director of Cantores. Nationally he has conducted concerts with NZSO, the National Ballet, NZ Opera and all the regional orchestras.
"For 10 years he conducted the annual summer ‘Opera in the Park’ and ‘Starlight’ concerts in the Auckland Domain."