Melissa McCarthy Surprises Mariska Hargitay on ‘Law & Order: SVU’ Set, on Video

Melissa McCarthy embraced her inner criminal on the “Law & Order: SVU” set … donning a disguise while pulling up to guest star on the long-running hit show.

The star shared a video on Instagram Thursday night shortly after her cameo on the show aired … which kicks off with her saying she wants to surprise Mariska Hargitay — going so far as getting a rubber mask to hide her identity.

It’s certainly not a “Mission Impossible” level identity concealer — but it apparently did the trick — because MH didn’t know MM was there until she walked onto the set in full costume.

Check out the clip … it takes Hargitay a few seconds to recognize McCarthy … but she goes berserk when she does, swearing in surprise and wrapping her fellow star up in a big hug.

McCarthy — dressed like a pro wrestler — cracks up at her pal’s reaction and tells her she’s there to cameo … and, Hargitay jokes they’ll need to rewrite the script for the star.

Of course, these two stars couldn’t help but play around … and Hargitay slapped a pair of cuffs on McCarthy in a hilarious end to the vid.

In case you haven’t seen the scene in ‘SVU’ yet … ya gotta check it out … McCarthy’s character gets real flirty with Hargitay’s Olivia Benson, including complimenting her “gams.”