In 1964, as Workington's player-manager, he led them into the Division 3 and left to become player-manager at Watford where he remained for several years, winning promotion to Division 2 for the first time in the club's history in 1969, and reaching the FA Cup semi-final a year later. He moved to Blackburn Rovers as manager in 1971 for two seasons before being announced as the new manager of Sheffield United on 9 December 1973.
Despite financial difficulties due to the building of the new South Stand, he led United to sixth place in the First Division, a 0-0 draw away to Birmingham City on the last day of the 1974-75 season left them just one point short of a UEFA cup place. However, the following season started disastrously with just one win from 11 games and his contract was terminated on 6 October 1975. Furphy left for America to manage the New York (1975–76) in the NASL. He also coached the Miami Toros (1976–1977), the Detroit Express (1977–80) and the Washington Diplomats (1981). He has also managed the national team of Bermuda and the Cleveland Force.
During the 2000/01 season he was appointed as a "Technical Director" of Exeter City, to help then manager Noel Blake as the club battled against relegation, however this tenure was short lived and he left the club after just 6 days in the job.
He has also worked for BBC Radio Devon's sports department, commentating on local football matches.