Yeah, might wanna get that tissue box ...

Here's the backstory ... WWE legend Mick Foley met 11-year-old Branden a few months ago at a barbershop in Florida and they bonded over their love of pro wrestling.

In fact, Branden was all set to attend WrestleMania 36 in Tampa to watch his favorite wrestler, Becky Lynch ... but due to the COVID-19 pandemic, fans are no longer allowed at the event.

Mick tells TMZ Sports ... he was trying to think of ways to lift Branden's spirits -- so he reached out to Becky to see if she would send him an uplifting video message.

AND, BOY, DID SHE DELIVER!!!

"Hi Branden it is ‘The Man’ Becky Lynch," she said ... "I hear that you’re a huge fan and I want to thank you for all of your support!"

Ya gotta watch the video -- not only does Becky say she's dedicating the match to him, but she adds, "I'll make you proud!"

We also got video of Branden's reaction when his parents played him the video -- amazing stuff!

Of course, gotta give a HUUUUGE shout out to Mick Foley for making it happen -- the WWE Hall of Famer has been on a mission to spread joy and cheer ever since the pandemic began.

Foley says his goal is to make 1,000 FREE videos to send out to fans all around the world because he knows it will make people smile.