Lionel Watson played junior football with Laurel Rovers and High Park before joining Manchester City in 1901. He only played one game before moving to Blackburn Rovers in 1902. Over the next two seasons he scored 18 goals in 55 games and was the club's top scorer during the 1903-04 season. Watson joined West Ham United in 1905. He made his debut against Swindon Town on the first day of the 1905-06 season. He developed a good relationship with fellow strikers Harry Stapley, Billy Bridgeman and Fred Blackburn. In the 1906-07 season Watson and Stapley scored 34 goals between them. Watson joined Blackpool in 1908.