The Kiwis bounced back from the loss of two competition points over the Nathan Fien ineligibility fiasco to score six tries to one and give themselves the upper hand of reaching the final against Australia.
Great Britain must now defeat Australia next week to qualify for the final.
Faced with a 28-point differential before the match, Kiwi coach Brian McClennan put pressure on his side by demanding a 14-point winning margin.
Once again, evergreen halfback Stacey Jones was the key for his side as he set up four tries and landed five of his six conversion attempts.
In comparison his opposite number Sean Long had a night to forget as he failed to recapture his best form from the previous week's victory over Australia.
Passions ran high throughout the match and rival centres Steve Matai and Keith Senior both spent time in the sin-bin following an early altercation.
Keith Senior: A week is a long time
in Rugby League
The Lions had two tries disallowed through the match, although neither decision could be seen as overly controversial.
Just before halftime Gareth Raynor was deemed not to have control of the ball as he dived over the line, and in the second spell Paul Wellens ran interference when Leon Pryce carved his way to the line.
But the home side were simply the better side as they controlled more of the ball and showed a real sting in attack.
Nigel Vagana had them on the board first in the 10th minute when he forced his way over the line in a three-man tackle.
Vagana, the Kiwis' record try scorer, defied Terry Newton, Jamie Peacock and Paul Wellens to notch his 19th international try to calm the Kiwis' nerves after an anxious beginning.
That ignited a short, sharp scoring burst where Brent Webb scored after Jones doubled around Sean Long.
Brent Webb: Two try hero
The Leeds bound fullback then had his side when he burst through the line to score again.
The only British try came between Webb's double when New Zealand winger Manu Vatuvei gifted them four points with an elementary mistake from a cross field kick.
The Kiwis led 16-4 at halftime, and extended their lead 10 minutes into the second stanza when Nathan Cayless dived on a deft Jones kick into the in goal.
Minutes later Vatuvei made amends for his first-half error when he finished off an orthodox backline move to cross wide out.
With 10 minutes remaining, Kiwi skipper Ruben Wiki rounded off the scoring spree when he gathered up a Jones kick which bounced off the cross bar.
The New Zealand captain arguing his side's victory was based on ignoring the pressure of winning margins.
"We just went out and didn't worry about the points," he said. "We stuck to the plan and we really enjoyed it today."
Great Britain captain Jamie Peacock rated his side's performance as "very poor."
"We were ordinary to say the least with the ball and I'm very disappointed," he said. "It's not the way we trained or played last week so we are going to have to improve next week."