How long has Justin Timberlake Been singing?

Justin Timberlake began his singing career as a child. He first appeared on television at the age of 11 on the talent show Star Search. He later joined the cast of the Disney Channel show The Mickey Mouse Club, which he appeared on from 1993 to 1995. In 1995, he and some of his fellow castmates formed the group NSYNC, which went on to become one of the most successful boy bands of all time. NSYNC released their first album, *NSYNC, in 1997. The album was certified diamond by the Recording Industry Association of America (RIAA), indicating sales of over 10 million copies in the United States. The group released two more studio albums, No Strings Attached (2000) and Celebrity (2001), which were also certified diamond by the RIAA. NSYNC went on hiatus in 2002, but Timberlake continued his solo career.

So, to answer your question, Justin Timberlake has been singing professionally since the early 1990s.