Nicki Minaj stepped up to bail out her brother Jelani Maraj ... after his arrest for raping a preteen.
Nicki put a $100,000 bond to get Maraj out of jail Friday in Nassau County, NY. He stands accused of first degree rape and first degree sexual conduct with a 12-year-old.
According to the NY Post ... court docs show Nicki used 2 of her homes in NY as collateral for the bond.
She's very tight with Jelani -- you'll recall she dropped $40k for his wedding back in August.