As we previously reported ... cops clocked Richardson speeding at 143 MPH with his 12-year-old nephew in the car when he was a member of the NY Jets back in 2015.

Oh yeah ... and he had a gun in the car.

He was charged with resisting arrest, excessive speeding, failing to obey traffic control device among other violations at the time ... but later copped a plea deal and was given 2 years of probation and 100 hours of community service.

The newest Cleveland Brown reflected on the incident with reporters on Thursday ... saying he's done a lot of growing up and can't be taking those kinds of risks.

"I was 24 in a Bentley, having a good time, that was it," Richardson said ... "I've got a daughter now, so I can't be doing 150 MPH on a highway."

Richardson welcomed his daughter, Riley Rose, back in 2016 ... and he says it completely turned his life around.

"I got a lot to live for."

Of course ... Richardson admitted his mistakes back in 2015 and vowed to make the right moves to get back on track ... and it sounds like he's still holding to his promise.