In 1971 he began to sing solo, under the name "Robert Long", a reference to his height.

On 8 September 2005 Long suffered a myocardial infarction and was treated with angioplasty. Later that year, on 6 December 2005 Long married his Belgian boyfriend and manager Kristof Rutsaert, 28 years his junior. The marriage ceremony was performed by fellow singer and actor Gerard Cox, a close friend of Long. On 4 December 2006 it was announced he was suffering from a terminal illness as he was admitted to hospital with cancer. Robert Long died on 13 December 2006 at 11 pm in a hospital in Antwerpen at the age of 63.