The Charlatans and Utah Saints will also perform at the two-day event held at the island's Rabbit Warren in Saint Sampson.
It will be the second festival held in Guernsey after it was launched in 2011 with headliners Ocean Colour Scene and Primal Scream.
Macy Gray will headline the opening night on June 23, with Kaiser Chiefs taking to the main stage the following day (June 24).
King Charles, Kassidy, Little Barrie and General Fiasco are also on the longlist of artists who will attend the Channel Islands event.
Kaiser Chiefs announced their greatest hits compilation Souvenir earlier this week, to be released on June 4.
> Kaiser Chiefs: 'We crave mainstream success'
The lineup for the Guernsey Festival so far is as follows:
Kitten And The Hip
Courage Have Courage
The Electric Stars
The Spindle Sect
In Tyler We Trust
Master And Dog
Watch the video for Macy Gray's 'Beauty in the World' below: