It's hugely significant because if he was convicted of a violent felony, he could have been deported -- which would have had a major impact on his UFC career.

Here's what happened inside the Brooklyn courtroom on Thursday -- Conor accepted a plea deal in which the felony count was dismissed. He pled guilty to a misdemeanor disorderly conduct charge.

He was sentenced to 5 days of community service, ordered to pay for the damage he caused to the bus -- and ordered to complete an anger management course.

Outside the courtroom, Conor issued a short statement -- "I just want to say I'm thankful for the D.A. and the judge for allowing me to move forward. I want to say to my friends, my family, my fans, thank you for the support."

Sources tell TMZ Sports ... Dana White will not bar him from the UFC as he has other fighters who have engaged in illegal violence.

One of the reasons is that White believes the legal system has already exacted punishment on the superstar.

Conor's co-defendant, Cian Cowley -- who also participated in the bus attack -- got the same deal ... but with only 3 days of community service.

A spokesperson for the Brooklyn D.A.'s office tells TMZ Sports ... "This is a fair resolution that holds the defendant accountable, ensures restitution for the victims and requires the defendant to perform community service where he can reflect on his conduct and give back to society.”

As we previously reported, Conor's attorneys had been negotiating a plea deal in the felony mischief case -- filed after the UFC champ threw a dolly at a UFC bus on April 5, injuring several fighters.

Conor was initially charged with 1 count of felony criminal mischief and 3 counts of misdemeanor assault.

Just last week, we were told prosecutors had agreed to reduce the felony to a misdemeanor -- which is a big deal since a felony involving violence could trigger permanent deportation from the U.S.

The 30-year-old UFC fighter faced up to 7 years in prison if convicted on all counts.