After playing for Manchester Schoolboys, Viollet joined United as an amateur in the 1949-50 season, turning professional at the age of 17. He was one of the many players of this era to have graduated from United's 'nursery' system, which produced players such as Duncan Edwards, Eddie Colman and Bobby Charlton. He was one of the 'Busby's Babes' who won a League Championship medal in 1956 and 1957, partnering Tommy Taylor in United's attack. Although Viollet lacked the physical attributes which were so evident in his team mate Taylor, he was a forward of the highest class with an enormous amount of skill and vision. His greatest attributes were pace and accurate shots. He still holds the Manchester United goal scoring record, 32 League goals in one season (1959-60). His actual tally for all first team games was 179. Considering Viollet made 294 appearances, his return of goals speaks for itself. In 1958 he was one of the players who journeyed to Belgrade for the quarterfinals of the European Cup, scoring one of the goals in a 3-3 draw. The game of course lost all significance in the wake of the events that followed the match. He was one of the lucky players, escaping from the blazing wreckage at Munich Airport, with injuries which were initially thought to be career threatening. However, he recovered in time to take his place in the 1958 F.A. Cup final, only to see United's courageous efforts thwarted by Bolton Wanderers. In 1962 he surprisingly left Old Trafford to join Second Division Stoke City. There he won a Second Division Championship medal (1962-63) and a League Cup runners' up medal (1964). After spells in America and the Irish League with Linfield, where he won an Irish Cup winners' medal, he emigrated to Baltimore in the early 1970's. He later moved to Florida, where he coached youngsters. Such was his work in this area that he was granted the freedom of the City of Jacksonville in the late 1990's.

Viollet joined the Richmond Kickers in their third season and immediately turned the club around, guiding it to its first winning season (15-3), the Premier League (PDL) title and the U.S. Open Cup championship, where it downed the El Paso Patriots in penalty kicks after a 1-1 draw. The club moved up to the Select League (Third Division) the following year and led the team to a 10-8 season, reaching the final before falling to California, 2-1, via a shootout. His two-year stint with the Kickers concluded with a regular season record of 25-11 and a postseason mark of 4-2.

On the March 6, 1999 Dennis Viollet died at his home in Florida after battling against a malignant brain tumor. The following day Manchester United played Chelsea in the quarterfinals of the FA Cup, all the players wore a black armband as a mark of respect. During his career, Dennis Viollet represented the Football League on the three occasions and won only two England Caps, scoring once. The lack of international recognition still remains a mystery to this day, as he was one of the country's top strikers during the late 1950's and early 1960's. Dennis Viollet was born in Manchester September 20, 1933.