Kim Zolciak got her wish -- her whole family went to a John Legend show and even got to meet him ... and her daughter didn't have to put out.

You may recall ... Kim joked with John's wife Chrissy Teigen earlier this month that her daughter Brielle would trade oral sex for VIP access. Some of her followers got upset -- but Kim told us it was an innocent JK.

Kim and Chrissy clearly don't give a rat's ass what anyone thinks. Also, the joke worked ... Kim's son Kash -- who's a huge Legend fan and is recovering from an operation -- got to meet the musician with the whole fam.

Brielle was also down with it ... you'll excuse the expression.