President Donald Trump and Dana White might've just had the best walkout of the night, before a single punch was thrown, arriving on the South Lawn in style!

After a short rain delay -- thunderstorms were in the area -- POTUS and his longtime friend walked out of the White House's West Wing, to a balcony overlooking the Octagon ... as a 4,000-strong crowd, many military members, cheered from the stands.

Trump saluted while White held his hand over his heart as the National Anthem was played ... culminating with several U.S. military jets doing a flyover.

After the anthem, the president and Dana walked a red, white, and blue carpet to their seats just feet from the Octagon.

When Joe Rogan got on the mic for the first time ... he summed up the atmosphere like this.

"It's such a scene. It's so surreal. It's so amazing. The energy is in the air. We're outside. We thought it might be called off for rain, but we're good. The whole thing is nuts!"

Of course, Freedom 250 is a historic event ... it's the first time a sporting event has ever been held at the White House.

The card features seven fights and is anchored by a highly anticipated title fight between Justin Gaethje and Ilia Topuria.