Play video content EXCLUSIVE TMZ.com

Comedian Russell Peters got involved in a serious situation at a jewelry shop, when he hopped to action and helped take down a wannabe thief ... and it's all on the security footage.

In the vid, obtained by TMZ, Peters is seen walking around the NYC Diamond District store Tuesday scoping some bling with one of the workers, while a man in a dark stocking cap is being attended to nearby by another employee.

All of a sudden, the guy in the cap gets up and darts away but gets stopped at the door ... which gets Russell's attention. The employee appears to try to apprehend the man, who gets physical and tries to make a break for it, but Peters and the other worker quickly grab him and hold him down before an officer shows up.

Law enforcement sources tell us the 27-year-old perp attempted to make off with a ring valued at $150,000 before he was apprehended by witnesses. Peters is listed on the police report as one of those witnesses.

If you're surprised the funny man is such a badass, don't be. Russell's trained in jiu-jitsu for years under famous black belt Jean Jacques Machado, who also trains Joe Rogan.

Basically, the suspect's lucky Russell only slapped an armbar on him!

Cops have charged the man with robbery and criminal possession of stolen property.