The host nation produced an emphatic response to Eloni Vunakece's first-half try with a dominant showing after the break.
It took until the 38th minute for Steve McNamara's men to get off the mark, but Ben Westwood's score was a sign of what was to come in the second half.
Further tries from Sam Burgess, Brett Ferres, Ryan Hall (two) and Rob Burrow added a degree of comfort for England, who will be joined by Fiji in the quarter-finals if Australia beat Ireland.
In two previous meeting between the sides, both in World Cups, England had prevailed by an aggregate score of 112-10, but this Fiji outfit posed an entirely different challenge in the opening 40 minutes.
Poor handling from Burgess denied England the perfect start, while their opponents ruffled a few feathers with an overtly physical approach, highlighted by Korbin Sims' spear tackle on James Graham, which saw him put on report.
The hosts thought they had taken the lead 20 minutes in, but Burgess had the ball slapped from his grip by Ashton Sims as he dived for the line.
Fiji's celebrations were cut short two minutes later when Daryl Millard's try was chalked off for an off-the-ball tackle on Sam Tomkins, whose fumble had led to the opening.
The South Pacific islanders stunned the home crowd in the 34th minute as Vunakece, off the bench only five minutes earlier, put them ahead.
Westwood's response was almost immediate, the Warrington second-rower collecting Kevin Sinfield's pass before touching down. Sinfield followed Kevin Naiqama's example in adding the extras.
England upped their game after the interval, Burgess' incredible drive-over effort putting them ahead within a minute of the restart and Ferres' converted try making it 18-6 two minutes later.
Hall increased his try tally for the competition to six with a double, sandwiching Burrow's effort, to take the contest away from Fiji before the hour mark, though they did grab a consolation through Semi Radradra Turagasoli Waqavatu.
Western Samoa or France await England or Fiji in the next round.