Kim and co. were able to get Usher to agree to be the newest face for their SKIMS Men's campaign -- and they got him to rock their underwear line for fellas ... including their SKIMS Stretch collection as well as their SKIMS Cotton collection.

As part of this new drop featuring Usher ... they're also releasing 4 new colorways.

It goes without saying -- the fact KK signed Usher to SKIMS is a huge deal ... especially since he's a well-known sex symbol, even these days. That's sorta alluded to in this photo shoot here -- where Mr. Raymond is baring his torso, with his chiseled abs on display.

BTW, there was a video filmed for this team-up as well ... and in it, Usher talks about why he signed on, but more importantly -- how it relates to this new album of his, "Coming Home."

Based on what he says here, you could argue this is a full circle moment for him -- Usher seems to be leaning into his R&B roots ... including what made him uber popular to begin with, like his killer looks. There's a limited edition digital version of his album that's dropping as part of the partnership ... it's releasing on Feb. 8 at 9 PM PT/Feb. 9 at midnight ET.

As for these new SKIMS products themselves ... the undies are gonna be up for grabs starting Feb. 12 at 9 AM PT -- you can obviously get 'em on the SKIMS Men Shop website.

Usher's addition to the lineup comes on the heels of Kim snagging other hunks in the industry to advertise her company -- remember, she already got Neymar Jr., Nick Bosa and other hot dudes to rock the gear ... and now, Usher is in the mix as well.

SKIMS is low-key taking over the fashion world -- everyone seems willing to strip down and pimp the product ... making ya wonder, how the hell do these things feel in person.