Born on January 5, 1944 in Waterford, County Waterford, Stewart grows up in Dublin. He begins playing guitar when he is thirteen, influenced by guitarists Les Paul and Barney Kessel. He begins his professional career performing in Dublin showbands. In 1968, he wins an award as the most outstanding soloist at the Montreux Jazz Festival. Soon after, he spends three years with Benny Goodman.
Stewart records his debut album, Louis the First, in Dublin, and then records in London with Billy Higgins, Peter Ind, Sam Jones, Red Mitchell, and Spike Robinson. From the mid to late 1970s, he works with George Shearing, touring the United States, Brazil, and playing European festivals, and recording eight albums, including several for the MPS Records label in a virtuosic trio with Shearing and the Danish bassist Niels-Henning Ørsted Pedersen. He also appears on albums by Joe Williams and J. J. Johnson, and works with many other jazz musicians.
In 1981, ahead of Stewart’s debut in the United States as a leader, The New York Times states, “Mr. Stewart seems to have his musical roots in bebop. He leans toward material associated with Charlie Parker and he spins out single-note lines that flow with an unhurried grace, colored by sudden bright, lively chorded phrases. His up-tempo virtuosity is balanced by a laid-back approach to ballads, which catches the mood of the piece without sacrificing the rhythmic emphasis that keeps it moving.”
Stewart is prominently featured in Norman Mongan’s book, The History Of The Guitar In Jazz, in a chapter devoted to guitarists who are considered to be contemporary masters (along with players such as Jim Hall, Pat Martino, and George Benson). In a review of his live album Overdrive (Hep, 1993), AllMusic states, “Louis Stewart is one of the all-time greats, and it is obvious from the first notes he plays on any occasion.”
Stewart receives an honorary doctorate from Trinity College, Dublin, in 1998. In 2009, he becomes only the second jazz musician to be elected to Aosdána, an Irish affiliation of people engaged in literature, music, and visual arts that was established by the Irish Arts Council in 1981 to honour those whose work has made an outstanding contribution to the creative arts in Ireland.
In 2015, Stewart is diagnosed with cancer and dies on August 20, 2016 in Harold’s Cross, Dublin, at the age of 72.