The southern Italian outfit edged out Juve Stabia 1-0 to move 24 points clear of third place, with the top two guaranteed promotion.
Inzaghi’s men have only lost once in Serie B all season.
Benevento previously played in the top flight in the 2017-18 campaign, when they infamously set the record for most consecutive defeats to start a season in one of Europe’s top five leagues, suffering 14 straight losses.
It was a run that was snapped when goalkeeper Alberto Brignoli’s injury-time header grabbed a dramatic draw with Milan.
Benevento were still relegated that term, but will now get a second crack at Serie A under World Cup winner Inzaghi.
beIN SPORTS, the biggest show