Post Malone is paying tribute to Kurt Cobain's iconic band with a special concert from home, featuring Nirvana songs ... and it's all for coronavirus relief charities.

The singer put up a somewhat cryptic video Wednesday, showing himself sitting on a stool onstage, with an acoustic guitar in hand ... while an unseen crowd cheers in the background. It's very reminiscent of Kurt's famous ''MTV: Unplugged'' show from back in the '90s.

After the footage plays, a title card reading "Post Malone Nirvana Tribute Livestream" flashes on the screen teasing a Friday YouTube special.

Our sources say Post wanted to honor the Nirvana frontman this month, which marks the 26th anniversary of his death. In the same breath, he also wants to help out in the COVID-19 fight.

Post will have a donate button on his YouTube page on the day of the at-home special -- which we're told will be shot at his living room bar -- and the cash will go toward the United Nations Foundation’s COVID-19 Solidarity Response Fund for the World Health Organization -- a newly-created org that uses funds to help train and equip communities to detect and fend off the virus on the ground. YouTube's matching all of PM's donations.

It sounds like the music will be strictly Nirvana, although it's possible he might sprinkle a few other songs in there too.

FYI ... he's got a tattoo on his face that reads "Stay Away," after the Nirvana song of the same name. So yeah, better than average chance you'll hear that one come Friday.