The founding members of the group were Conleth (Con) Cluskey (born 18 November 1941), Declan (Dec) Cluskey (born 23 December 1942), and John Stokes (Sean James Stokes) (born 13 August 1940). In 1957 they formed their first band together, "The Harmonichords" (also seen as "The Harmony Chords"), a classically styled instrumental harmonica-act.

As The Harmonichords, they appeared on Hughie Green's 'Opportunity Knocks' on Radio Luxembourg and on the the 'Ed Sullivan' TV Show St. Patrick's Day Special (filmed in Dublin, aired March 15, 1959), where they played "Danny Boy."

They also played background music plus featured pieces in a 25 week radio comedy series called 'Odd Noises' on Radio Éireann featuring Eamonn Andrews. They changed their name to "The Bachelors" in 1962 at the suggestion of Dick Rowe, A&R at Decca Records, who reportedly recommended the name "because that’s the kind of boy a girl likes."

During the 1960s, they had many successful songs in music charts in Europe Australia, South Africa, South America, parts of the USSR, and the United States. Some of the most successful were "Diane" (1964), "Marie" (1965), "I Wouldn't Trade You For the World" (1965), and "In the Chapel in the Moonlight" (1965). In 1965 they had the 'most played juke box track' with "The Stars Will Remember" from a film they made with then-current DJ Sam Costa.

Live work carried them into the 1970s with record breaking theater season shows, but after a successful start to the decade with the album World of the Bachelors hitting the top 5, the band became less and less dominant in the music industry. Along with singers like Tom Jones they found themselves stuck in a decade of Glam Rock, unable to change with the times.

They remained successful recording artists and moved to the Pye label, which contracted easy listening stars like Frankie Vaughan and Max Bygraves. By 1979, however, without a hit single in almost twelve years, the cracks were showing.

In 1984 there was a falling out between the members of The Bachelors, and John Stokes was asked to leave the band at a meeting held in The Eccentric Club in London. He was also removed as a director of Bachelors Limited.

After a High Court case, John Stokes was not allowed to use any name containing the word Bachelors ["or any colourable imitation"], whilst Con & Dec were allowed to use any name that contained the word Bachelors [except The Bachelors alone or The Original Bachelors].

This was contained in a legal undertaking which John Stokes signed with Con & Dec Cluskey when he bought the company 'Bachelors Ltd' from them. Meanwhile Con & Dec recruited a new member, Peter Phipps, and continued until 1993 as The New Bachelors.