Al Sharpton is putting his money where his mouth is ... offering $50,000 for information leading to an arrest and conviction in Nolan Wells' death ... and Tyler Perry is following suit.

Sharpton announced the reward Monday while delivering remarks at the 18-year-old's funeral ... saying he and the National Action Network are ready to put up the cash.

Watch the clip ... Sharpton says anyone with information can contact attorney Ben Crump's office. Crump is representing Nolan's family.

Sharpton said Nolan "was not on that island by himself" and insisted somebody knows more about what happened during the Fourth of July trip to Mississippi's Horn Island, where Nolan was found dead two days after going missing.

Sharpton guaranteed the rewards would be paid before sundown if a tip leads to an arrest and conviction.

Colin Kaepernick previously stepped up to pay for an independent autopsy ... and Tyler paid for the funeral services.

The reverend also fired back at the anonymous person who suggested he and Crump were exploiting Nolan's grieving family, declaring ... "I didn't come to make money, I came to give money."

As TMZ previously reported ... Nolan's mother, Christine Wonsley, received a defaced photo showing dollar signs drawn around her while Sharpton and Crump stood nearby ... seemingly accusing the men of cashing in on her grief.

Nolan disappeared after traveling to Horn Island by boat with friends, who said he remained behind without his phone. His body was discovered in the water two days later.

Authorities have said they believe Nolan drowned and investigators had not found evidence of a crime ... but his family continues to question that conclusion and is conducting an independent investigation with Crump's help.