The judge was convinced a conviction would provide "a real impediment to what so far has been a stellar career".
"All indications are you can go all the way in rugby," he said.
The court heard how a conviction may have restricted Li's international travel playing rugby and if he later pursued a career overseas, teams may overlook him because of the black mark against his name.
His clean record will now keep the door open for a career in the police once he has finished playing rugby.
Li's lawyers previously told the court he wanted to follow the path other family members took into the force and Judge Andree Wiltens said there was inconclusive evidence as to whether that may be possible with a conviction against his name.
One of the swaying factors in favour of the defendant was his completion of The Right Track programme.
The course, which covers 42 hours over four weeks, is usually attended by young recidivist drink drivers to bring home the seriousness of their offending.
Li had also received counselling for his alcohol use.
The court previously heard how Li had been stopped at a police checkpoint while driving on May 11.
He had spent the night at a friend's house after drinking.
Li rose to prominence at 16 while playing for his Massey High School and after just one match for the Massey Club, the young back was offered a full-time contract with Super 15 champions the Chiefs.
But he opted for his home-town team and made his Blues debut against France last year before impressing for the national under-20 team at this year's Junior World Cup.
Li's teammate George Moala was found guilty of assault with intent to injure after a trial earlier this month.
He too will apply to be discharged without conviction when he is sentenced in May.
