Nuno Espirito Santo's side was fortunate to avoid an embarrassing upset after a lacklustre display at Victory Park.
Vitinha's brilliant long-range drive put Wolves ahead early in the first half.
But sixth-tier Chorley, the last non-League club standing in this season's competition, pushed Wolves all the way and could easily have forced extra-time.
Wolves keeper John Ruddy had to make several good saves before they secured a Round of 16 tie against Southampton or Arsenal.
Wolves are winless in their past six Premier League games and Nuno will hardly have been encouraged that a revival is around the corner after their trip to suburban Lancashire.
Nuno made six changes from last weekend's loss to local rival West Bromwich Albion, but still included the likes of Conor Coady, Joao Moutinho and pre-season signing Fabio Silva.
Reflecting the huge divide between the teams, Chorley captain Scott Leather booked the day off from his job as a lift engineer to play for the part-timers.
Many of Leather's team-mates spent the day at work, including manager Jamie Vermiglio, who is a primary school headteacher.
Having beaten Wigan Athletic, Peterborough United and Derby County, National League North Chorley was enjoying its best ever FA Cup run and gave Wolves a real scare as well.
It almost snatched the lead when Harry Cardwell picked out Elliot Newby's run into the Wolves area and he brought the ball down on his chest before firing a low shot that Ruddy smothered.
With houses lining the tiny ground, some locals got a free glimpse of the action from their gardens, while a cardboard cut out of celebrity Chorley fan and pop star Adele sat in one of the stands.
Fireworks were let off from one house to encourage Chorley, but it was Vitinha who provided the pyrotechnics in the 12th minute.
Taking possession 35 yards from goal, Vitinha set his sights and unleashed a ferocious, swerving drive that flashed over startled Chorley keeper Matthew Unwin.
Vitinha was the 11th different Portuguese player to score for Wolves since Nuno took charge.
It is doubtful Unwin faced many shots of that quality in the National League North, but the on-loan Porto midfielder's first senior goal was Wolves' only strike on target in the entire game.
Patrick Cutrone did go close for the visitors with a rising drive that just cleared the bar.
Connor Hall, who scored in the first, second and third rounds for Chorley, threatened an equaliser when his header forced Ruddy to save early in the second half.
Wolves were struggling to keep Chorley at bay and Ruddy had to tip over Andy Halls's header before the plucky underdogs eventually ran out of steam.