He commenced his musical career in 1962. In 1972 he relocated to New York and worked in a quartet with Colombian pianist Eddie Martínez. After a six-month stint performing in Puerto Rican hotels, he returned to New York and replaced Adalberto Santiago as lead singer of Ray Barretto’s band for the 1973 album Indestructible, which included Martínez on piano. Allen then made a series of seven woefully under-promoted albums on the Alegre label between 1975 and 1981, corresponding with the period of Alegre’s absorption by Jerry Masucci’s Fania Records empire and its eventual demise. In 1976 Allen again filled a slot vacated by Santiago when he took over as lead vocalist with Típica 73 on their Rumba Caliente. He also took time out from his solo career to record with the Puerto Rico All Stars (1977) and Tito Puente (1979). In 1981 Allen recorded Cantar with Conjunto Clásico on their Lo Mejor label.