Mixon partnered with Strikes for Kids for the special event ... hooking up 28 youngins at the local Boys & Girls Club with some wheels just in time for Christmas.

TMZ Sports is told ... the kids were taken to Main Event Entertainment Center in West Chester, where they enjoyed two hours of unlimited games, pizza and Icees.

As they had tons of fun, they were surprised with new bikes and helmets ... as the 25-year-old posed for pics with them.

Of course, the kids couldn't wait to try out their new wheels ... moving around inside the event space to get in a quick ride.

Mixon spoke about his decision to help out ... saying, "This community has embraced me and become a second home for me, so to be able to give back and inspire these children is the least I can do."

Mixon's kind gesture comes on the heels of notching yet another 1,000 yard rushing season -- the third time the RB has done so in his career.

It's clear he's a difference maker for the Bengals -- on and off the field.