Packers star pass rusher Za'Darius Smith is putting some serious heat on his OWN quarterback, telling TMZ Sports ... Aaron Rodgers needs to marry Danica Patrick ASAP!!!

"Look, 12, I know I'm on TMZ," Smith hilariously told us out at Super Bowl festivities in Miami on Wednesday ... "But, man, most definitely, you should marry that lady!"

Rodgers and Danica have been dating for over two years ... and things are definitely SERIOUS between the two.

They've publicly said "I love yous" ... she's rooted him on at Packers games, despite being a Bears fan ... and the two even just bought a $28 MILLION mansion together in Malibu.

But Rodgers has yet to bend the knee and pop the question ... and Za'Darius tells us his QB needs to change that.

"She's a lovely woman," Smith says. "I've met her."

In fact, Smith says he thinks Rodgers giving Danica a ring could elevate the QB's game ... telling us his own career really took off once he committed to his GF during his Baltimore Ravens days.

"She kept me locked in," Smith said.