Mike Tyson's Down To Fight Anthony Joshua For Charity

54-year-old Mike Tyson says he would fight 30-year-old, 6'6", 240 lb. heavyweight champion Anthony Joshua, RIGHT NOW ... as long as the money went to charity!!

Some background ... Rafael Cordero, Mike's legendary trainer recently told us that Tyson -- who last fought in 2005 -- could hang with beasts like Joshua, Deontay Wilder, and Tyson Fury.

So, when "Iron Mike" joined the "TMZ Sports" TV show to talk about his HUGE Legends Only League fight with Roy Jones Jr. on November 28 ... we asked him if his next opponent might be a boxer in his prime.

Someone like ...  IBF, WBA, WBO, and IBO champion, Anthony Joshua?

"Listen, I'm very interested. If doing that means we can have a bigger charity exponent, well so be it, I'm down to do that, too."

Seriously??

"I would love to [fight Joshua]. That would be mind-blowing."

That's not all ... Mike also talks about voting for the first time this November in the presidential election, and what would've happened if he chose MMA, rather than boxing back in the day.

Full interview airs tonight on FS1 at 9pm PT / 12am ET on FS1!