He published several songs in the late 1960s and went on tour, with moderate success. In late 1967, at age 19, he entered a hospital and was diagnosed with tuberculosis; his career seemed over. He had a comeback in the early 1970s however. In the ten years after 1967 he sold 40 million albums.
His most popular songs included "Peace Train," "Morning Has Broken," "Moon Shadow," "Wild World," and "Father and Son." Many of them were performed only with him playing the guitar. In 1971 he also wrote music specifically for the film Harold and Maude. For several decades these songs were unavailable except on the film; most of them have since been released on the disc Footsteps in the Dark.
He converted to Islam in 1978, changed his name and abandoned his previous carreer as a pop star. At one point he wrote to the record companies, asking that his music no longer be distributed; the request was denied. He appears to have changed this position, as his web site today lists the available albums. He states that much of the royalities are given to charity.
His comments in 1989 concerning Salman Rushdie after the publication of Rushdie's novel The Satanic Verses provoked controversy. During this time period an Islamic fatwa (religious ruling) was issued, holding that it was an obligation of Muslims to kill Salman Rushdie. Yusuf Islam publicly stated that Rushdie was indeed guilty of blasphemy against Islam, and Rushdie deserved to be killed. This led to a public outcry, and a drop in record sales. In response to this criticism, Yusuf Islam has since clarified that he believes that a death sentence can only be carried out by the authority of a court in an Islamic society, and that he is opposed to anyone taking the law into their own hands by murdering Rushdie.
He has resumed making Islamic music choosing to use only the human voice and basic percussion instruments in the compositions. He has also released the album A is for Allah, an instruction for children. He has been instrumental in creating a web site called Mountain of Light (link below).
He lives with wife and five children in London, where he is an active member of the Muslim community. He founded the charities Muslim Aid and Small Kindness to assist African famine victims.
In 2003 Cat Stevens recorded "Peace Train" once more for a compilation cd which included David Bowie and Paul McCartney and performed in Nelson Mandela's 46664 concert with Peter Gabriel, recording and performing English music for the first time after 25 years.
"This issue of music in Islam is not as cut and dried as I was led to believe," he said. "I relied on heresy, that was perhaps my mistake."