Lawrence Watson was born Laurence White Watson on 2 May 1860 on Queen Street, Charlottetown, and baptised at St. James Church in Charlottetown on 11 July 1860. His father was William R. Watson and his mother Sarah Ann Watson (nee Sarah Ann Croskill). (The official baptismal record shows his name as Laurence but the spelling changed from Laurence to Lawrence at some point.) Watson dies in Charlottetown on 17 July 1925, age 65. According to the obituary in The Charlottetown Guardian newspaper on 29 July 1925, Watson received his B.A. at King's College, Windsor, Nova Scotia in 1879, and then studied medicine at the University of Edinburgh, Scotland (1880-1882). He ended his medical studies on the death of his father and returned to Prince Edward Island to continue his father's business.
In 1884, Watson became the organist at St. Peter's Cathedral Church, directed musical services for many years, and carried out numerous other duties for the church. He was a founding member, officer and official historian of the National Historic Society and wrote many articles on natural history.
Watson composed the music for The Island Hymn, with lyrics by Lucy M. Montgomery.
Watson was married to Eleanor Massey Desbrisay. According to census records he had two children, Ruth (born ca. 1893) and Norman (born ca. 1899), but The Charlottetown Guardian newspaper indicates he had a daughter and two sons.