Small was born at Gibralter in Clarendon, Jamaica, the daughter of a sugar plantation overseer. Like many Jamaican singers of the era, her career began by winning the Vere Johns Opportunity Hour talent contest at the age of twelve. Wishing to pursue a career as a singer she moved to live with relatives in Love Lane in Kingston.In her teens, she recorded a duet with Owen Gray (“Sugar Plum”) in 1962 and later recorded with Roy Panton for Coxsone Dodd’s Studio One record label as ‘Roy and Millie’. They had a local hit with “We’ll Meet”.
These hits brought her to the attention of Chris Blackwell who became her manager and legal guardian, who in late 1963 took her to Forest Hill, London, where she was given intensive training in dancing and diction. There she made her fourth recording, an Ernest Ranglin rearrangement of “My Boy Lollipop”, a song originally released by Barbie Gaye in late 1956. Released in March 1964, Small’s version was a massive hit, reaching number two both in the UK Singles Chart and in the US Billboard Hot 100, and number three in Canada. It also topped the chart in Australia. Initially it sold over 600,000 copies in the United Kingdom. Including singles sales, album usage and compilation inclusions, the song has since sold more than seven million copies worldwide. Small was not a one-hit wonder. For example, subsequent recordings such as “Sweet William” and “Bloodshot Eyes”, both charted in the UK at numbers 30 and 48 respectively.
“My Boy Lollipop” was doubly significant in British pop history. It was the first major hit for Island Records (although it was actually released on the Fontana label because Chris Blackwell, Island’s owner, did not want to overextend its then-meagre resources; in the US, the record appeared on the Smash Records subsidiary of Mercury Records), and Small was the first artist to have a hit that was recorded in the bluebeat style (she was billed as “The Blue Beat Girl” on the single’s label in the US). This was a music genre that had recently emerged from Jamaica, and was a direct ancestor of reggae.
She appeared on the 1964 Beatles TV special Around The Beatles.
On 6 March 1965, Small appeared on the Australian television programme Bandstand. This was as part of a concert at the Sidney Myer Music Bowl in Kings Domain, Melbourne, part of the Moomba Festival. She performed “My Boy Lollipop”, “What Am I Living For” and “See You Later, Alligator”. Small continued to tour and perform up to the early 1970s.