"Singer", as the name would imply is a singing competition show much like "X Factor," but instead of showcasing new singers, "Singer" puts already renowned performers head to head. Jessie J won crowds over with her fashionable ensembles, appreciation for Chinese culture, and obviously singing chops.
Jessie J revealed in an interview following her win that she was "asked to compete in a singing competition in China... alongside the biggest established singer/artists across Asia." While no doubt Jessie J's enjoyed her "3.5 months" (Instagram) in China, Jessie J has certainly found a large market for her music. China is home to 1.38 billion people. (For comparison, Britain is home to 65.64 million people).
As you'd expect, Jessie J couldn't very well say she decided to go to China to build a fanbase for her music. Not at all. Jessie J's response was that she was trying to "bridge a gap between two cultures."
Marina Hyde, writer for The Guardian humorously noted that she believes the arrangement "to have been made in a bilateral Sino-British huddle during a session break of the UN security council."
Watch Jessie J's rendition of the Titanic theme song "My Heart Will Go On."