He joined the Daily Telegraph at the age of 15 in 1941, and began writing music criticism for it in 1948. He was Northern Editor of the paper from 1960 to 1986, joint chief music critic from 1986 to 2005, and chief music critic of the Sunday Telegraph from 1989 to 2005. He was on the Board of Governors of the Royal Northern College of Music from 1971 to 2006.
He was appointed an Officer (OBE) of the Order of the British Empire in 1981 and a Commander (CBE) in 1997. Michael Kennedy has been semi-retired since 2005.
As a writer, his main interests have been late Romantic music and the history of music-making in Manchester since the 19th century. He is particularly well known for acute and sympathetic studies of the works of Ralph Vaughan Williams (who was during his last years a close friend),Edward Elgar, and Richard Strauss. Perhaps his most significant book has been the second edition of The Oxford Dictionary of Music, published in 1994. He received an honorary doctorate degree in music from Manchester University in 2003. And in 2005 he was elected an honorary member of the Royal Philharmonic Society.