"He is a special player," coach Wayne Pivac agreed.
"His leg drive is superb and he always gets go forward ball for us. He just has to work on his decision-making."
Another whose work warmed Pivac was All Black lock Ali Williams, making his comeback after knee surgery. He played 60 minutes and dominated areas like the kickoffs and setpiece while skipper Daniel Braid also got back into action after a long injury layoff.
Auckland's victory assured them of a place in the playoffs with their match with Otago and other results determining their finishing order.
They were a little sloppy in the first spell but the strength of their scrum, Gareth Anscombe's kicking and the constant threat from Piutau kept them ahead of their hosts.
For Harbour, the pain continues. They are the most consistent side in this year's series after nine straight defeats with their Tasman match their last hope of breaking that sequence.
Auckland 36 (Charles Piutau, Dave Thomas, Gareth Anscombe, Daniel Braid, Angus Ta'avao, tries; Anscombe 4 con, pen.)
North Harbour 16 (James Parsons, try; Codey Rei 3 pen, con). Halftime: 24-16.