Singer Samantha J Inks HUGE Deal -- Jamaican It Rain!

'Memba mi tell yu, Jamaican singer Samantha J ah do big tings ... di pretty gyal just sign a record deal fi ah whole heap ah cheddar. Jah! Rastafari!!

Now, the translation: Samantha recently signed with Columbia Records -- and TMZ obtained a copy of the deal ... which will make the "Tight Skirt" star a very rich 17-year-old ... if she sticks with the label long enough.

The pay structure is set up so that Samantha's first album gets her an advance of at least $325,000 ... and as high as $700,000, if needed.

According to the contract -- if Samantha sticks with Columbia through her 6th album -- she'll collect up to a $1.1 million advance!

She's also getting fat royalties ... at least 16% of sales.

That's the kinda scratch that'll get Samantha ... one 'nuff yaad down ah Jamrock ... right near di beach, boyee!