The split was amicable, said Nicole Perna, a publicist for the pair.
The 44-year-old actress and 55-year-old singer have been engaged since March 2006.
They first started dating in 1992 and spent five years together, Perna said, then rekindled their romance in 2005.
Sheridan plays Edie Britt on ABC's "Desperate Housewives."
Bolton won Grammy awards in 1989 and 1991 for male pop vocal performance.
The couple's split was first reported by People.com.