Mike Tyson If I Win the Lottery, I'm Giving HALF to Piers Morgan

3/30/2012 1:20 PM PDT

Mike Tyson -- I'm Giving HALF My Lottery Winnings to Piers Morgan

It's on the record -- Mike Tyson officially promises to give Piers Morgan ONE HALF of his Mega Millions jackpot if he wins the lottery today ... this according to the boxing legend's rep.

In case you missed Piers' show last night, the CNN host gave Tyson a Mega Millions ticket -- saying, "You lost half a billion dollars. Here's your chance to win it back."

In return, Tyson now vows to split his winnings with Piers if he scores the $640 million jackpot.

A rep for Tyson tells TMZ, "Mike would definitely split the winnings with Piers Morgan if the ticket won ... he believes that is the right thing to do."

Unfortunately, it's already been decided ... we're gonna win that money. Sorry, everyone.