Harvey Weinstein's NYC rape conviction getting overturned has him so elated it's reduced him to tears as he sits in prison.

Weinstein's rep Juda Engelmayer tells TMZ she chatted with her client twice today, and he's over the moon about the news of the Court of Appeals ruling Thursday ... which determined his constitutional rights were violated back in 2020 during the trial.

However, Juda says the disgraced movie mogul -- currently incarcerated in an upstate NY State prison -- is only cautiously optimistic about the court's ruling, and knows he has a difficult road ahead of him, especially since it remains to be seen if and when he'll be prosecuted again.

But, he emphasizes the news clears a significant hurdle for Weinstein, and has moved him to tears because he assumed no judge would dare challenge the court of public opinion by overturning his conviction.

We're told Weinstein's very grateful to the appellate judges for reviewing the case thoroughly and understanding its merits.

As for the Manhattan D.A.'s Office vowing to TMZ it will spare no effort to retry the case, Juda says Weinstein has no response, and remains laser-focused on the court of appeals' decision and his newfound hope.

Weinstein hired criminal defense lawyer Jennifer Bonjean to appeal his 2022 L.A. conviction on 3 charges, including rape and forcible oral copulation.

She tells us the decision to overturn his NY conviction isn't surprising to her because she believes Weinstein didn't get a fair trial in the Big Apple, as she thinks the jury was overwhelmed with multiple uncharged allegations from his L.A. case.

Bonjean tells us if it were up to her, her client would be released immediately on bail pending appeal. She also explained why she thinks his L.A. conviction has to be overturned now ... due to the outcome of his NY appeal.

As you know, Weinstein was sentenced to 16 years behind bars in the L.A. case, and 23 years in prison in NY.