ALBANY, N.Y.—As state lawmakers debate whether to legalize mobile sports betting in the Empire State, New Yorkers wagered $837 million on sporting events in New Jersey last year, according to an industry-funded study released Tuesday.

That is almost a fifth of the $4.6 billion that was bet in New Jersey last year on sporting events, according to state figures. And for state Sen. Joe Addabbo, a Queens Democrat, it represents millions of dollars in tax revenue that is going to New Jersey but could help bridge New York’s budget...