LeBron James has a message to the most powerful people on the planet -- the time is now to "step up" ... and lead the charge to make the world a better place.

LeBron delivered his statement in a video introducing the first ever Bloomberg Global Business Forum in NYC ... which featured talks with HUGE names like Bill Clinton, Justin Trudeau, Bill Gates and Tim Cook.

"We all know what’s happening right now ... how hard it is suddenly to understand so much in this world," James said.

"You’re in this room for a reason ... we’re leaders. We all know the world needs us to step up."

The video montage touches on all the biggest issues facing our global economy -- from governmental unrest to climate change to emerging technology -- issues that LeBron urges everyone at the forum to tackle together.