Colin Kaepernick has another powerful ally ... Dave Chappelle.  

In fact, the comedian wore a shirt supporting the embattled QB on the way into his big stand-up show Thursday night at Radio City Music Hall in NYC. 

The shirts were being given out by the NAACP at the Kaepernick rally in front of NFL headquarters on Wednesday ... unclear if Chappelle was there or got a shirt after the fact. 

Chappelle wore a different shirt onstage for the performance -- but made sure people saw it on the way inside. 

As for Kaep, he finally spoke out about the rally on Twitter yesterday -- "Thank you to everyone who went out to support yesterday. My faith always has been and always will be in the power of the people!"