Music Crowns offers unsigned rock and urban acts the opportunity to win a year-long management contract, a website worth £1,000 and a Music Crowns trophy, by entering via its website musiccrowns.co.uk.
A winner will be picked in September after votes from the public and a host of judges, including UB40 singer Ali Campbell and US star Montell Jordan.
The winner will appear either in Skinny Water's TV ad at the beginning of next year, or have their song picked as its soundtrack.
Skinny Water is described by its maker, Bio-Synergy, as a dietary supplement that helps reduce sugar cravings.
In June, it will kick off its first marketing TV campaign for a year to promote the launch of its new dilutable drink, Skinny Grapefruit.
The drink will initially be available from Asda stores nationwide in a litre-sized bottle. More than 100,000 bottles will feature the Music Crowns logo.
Music Crowns founder Chris Mitchell said: "Having Bio-Synergy on board gives the winners a chance to create an inventive track for the ad, and offers another dimension to Music Crowns."