Nick Cannon has the blues.

The actor, musician and "American's Got Talent" impresario will "flip the switch" and light up the Empire State Building in blue at noon Wednesday to celebrate the good works of St. Mary's Healthcare System for Children.

Cannon, a former Nickleodeon star, is now the chairman of Nickleodeon's TeenNick network and is also on the board of St. Mary's Healthcare System for Children, New York's oldest children's hospital.

His lighting stunt today in the Empire State Building's lobby precedes his visit to the hospital's Queens campus and the "Nick Cannon ROCKS Times Square" event at the Hard Rock Café Thursday.

While the lighting ceremony is at noon, the Empire State Building will not be bathed "St. Mary's blue" lights until dusk Wednesday night. The ceremony kicks off a two-day celebration of kids who have been treated at the facility, which began in the 1870s, and is now the city's only pediatric post-acute care hospital.

Cannon, who married singer Mariah Carey in 2008 and filed for divorce in December, has 4-year-old fraternal twins with the superstar. He has reportedly inked a lucrative deal to write a tell-all about their troubled marriage.