The hosts scored eight tries -- Mack Hansen snaffling a brace -- and an eye-catching first start at fly-half by 21-year-old Sam Prendergast also gave the home crowd much to cheer.
Ireland will round off their November internationals against Australia next Saturday, with the return of former coach Joe Schmidt.
His successor Andy Farrell was delighted with both the overall performance and Prendergast's display.
"We played some really nice rugby, we were flowing at times," he said.
"We held our nerve pretty well. Our discipline was better. We was nice and composed.
"Sam pulled the strings well."
The Fijians never looked likely to add a second significant scalp to their belt having beaten Wales for the first time in Cardiff earlier this month.
The home side struck early as captain Caelan Doris went over for his seventh try in his 46th Test in the fifth minute -- Prendergast converted for his first points in international rugby.
However the youngster was in deep trouble a few minutes later as he was sin-binned for turning as Kitione Salawa stormed down the wing and his shoulder connected with the Fijian's head.
Fiji went close to punishing Ireland immediately but winger Jiuta Wainiqolo was judged to have been short when he touched the ball down.
These were nervy times for an Ireland side, who had been under-par in a defeat by New Zealand and then a narrow win over Argentina.
Prendergast breathed a sigh of relief on the sideline as he got the benefit of the doubt and his yellow card was not upgraded to a red.
Even in his absence his team-mates managed being a man down well and forced the Fijians into a series of infringements.
This paid off for the hosts as Doris fed Josh van der Flier and he went over -- Craig Casey converted in Prendergast's absence for 14-0.
Prendergast returned just as Fiji got points on the board, Caleb Muntz converting a penalty for 14-3.
However, referee Hollie Donaldson lost patience with Fiji and just after the Irish kick-off she wielded a yellow card at prop Eroni Mawi.
The Fijians' ill-discipline kept offering the Irish chances and Casey went over for his first try in his 17th Test.
Prendergast converted for 21-3.
The Irish rounded off a dominant first-half performance in style.
Prendergast came up with a delightful cross-field kick for Hansen to touch down and the Irish fly-half converted for 28-3.
- 'A lot more pleasing' -
Ireland pressed home their advantage from the off in the second-half.
Player of the match Bundee Aki rebounded from being dropped against Argentina to go over after another move full of flair from the hosts in the 46th minute.
Donaldson, though, humbly asked the TMO if she had been responsible for the hole in the Fijian defence opening up when she tumbled to the ground -- to her relief the answer came back 'no'.
Prendergast converted for 35-3 -- minutes later he was joined by his older brother Cian as he came on as a replacement.
The Fijians finally threatened the Irish tryline and Salawa went over -- Muntz converted for 35-10.
It did not herald a comeback as Prendergast's fellow Test debutant and former Ireland Under-20 teammate Gus McCarthy crowned it with a try.
Prendergast converted for 42-10.
Fiji came back immediately, 18-year-old Fijian Setareki Turagacoke taking Muntz's delicious offload to go over only minutes after coming on.
Muntz converted for 42-17.
However, Turagacoke's action-filled few minutes culminated with him being sin-binned and it paved the way for Hansen to go over for his second try.
There was still time for replacement hooker Ronan Kelleher to go over.
Doris, who will learn on Sunday if he has been named world player of the year, said it had been a much more clinical performance.
"A lot more pleasing than the last couple of weeks," he said.
"The message at half-time was to be ruthless and I think our attack was pretty good."
