John Mackay wrote his first song at 3 years old, and began piano studies at age 6. He began his professional career at age 18, playing the Hammond B-3 organ in a number of venues, including television and radio. He studied composition and arranging throughout the 70's with various well-known teachers in Toronto. He has worked with some of Canada's finest jazz musicians, including Peter Appleyard, Don Thompson, Marty Morell, Michael Stuart and many others, while simultaneously working some "commercial gigs" with various artists, including Roger Whittaker and Jim Carrey. John moved to the U.S. in the 80's and spent a couple of years gigging around New York, before settling in Boston for a number of years. While there, he worked with, amongst others, Cab Calloway and William Thomas McKinley.

John now divides his time between the USA and Canada, leading an active musical life, performing, recording, composing and teaching. He has released many recordings, mostly original compositions, including jazz, pop, sacred vocal music, contemporary classical and celtic. His most recent recording is a dedication to Canadian icon Gordon Lightfoot. John uses the jazz piano trio setting for unique arrangements of 10 of Gord’s beloved songs.

Twenty-four Forays into Classijazz features John as solo pianist playing twenty-four original compositions—one in each of the 24 keys—(in honor of J.S. Bach). He coined the term “classijazz” as a way of trying to describe the music. It celebrates his early study of classical music combined with his love of jazz. These forays have received a number of awards in composition contests over the past few years.

As a composer John is active in many different fields including jazz, contemporary classical, theatre, pop and electronic music. His theatrical song-cycle entitled "War is an Avalanche", based on Anzac letters from the First World War, received its world premier in Apr. of 2015, receiving rave reviews. He is presently working on a new musical theatre piece with well-known Canadian artist/writer Oliver Girling, based on the James Joyce novel, ‘Finnegan’s Wake’. Alongside that project he has created a 7 movement piece (short movements) around the famous Molly Bloom soliloquy at the end of James Joyce’s Ulysses. He is actively looking for collaborators for this project.

John’s music has won awards in contemporary classical, solo piano, choral, children's music and jazz genres.