Kamo crossed again soon afterwards through hooker Jordan Antonovich to give them a 15-7 lead before Otamatea's Daniel Hawkins brought the visitors within five shortly before halftime.
O'Grady came to the fore again to add to Kamo's lead as Wiki started to flex his playmaking muscles.
Impressive Kamo flanker Jordan Otene grabbed a try to extend the lead.
"We have a lot of confidence in our game plan now, working on a few other things. Looking to next week at Hora Hora's forward pack who are really strong, it's about eliminating them from the match."
Meanwhile Hora Hora picked up their second straight win, beating Hikurangi 27-20.
Hora Hora built off last week's win to pick up the tight victory, while Hikurangi fell to their first defeat of the season.
Old Boys Marist continued their dominance of the competition, comfortably beating Wellsford 48-5 to leave them as the only undefeated side in the competition.
OBM and Northland halfback Matty Marwick made the difference in the second half with a pair of tries, while Noah Cooper continued to show his class from fullback.
Wellsford toiled hard but were no match for the defending champions.
Mid Northern racked up a half century in their 50-7 rout of the winless Mid Western, while Western Sharks shut out Waipu 37-0 to give them their second loss.
Results:Premier: Hora Hora 27-20 Hikurangi Mid Northern 50-7 Mid Western Western Sharks 37-0 Waipu OBM 48-5 Wellsford Kamo 35-29 Otamatea
Reserves: Hikurangi 29-5 Hora Hora Mid Northern 26-0 Mid Western Waipu 17-8 Western Sharks OBM 22-10 Wellsford Kamo 47-22 Otamatea
North Zone: Kerikeri A 38-12 Kaikohe Kaeo 29-19 Kerikeri B Kaitaia 35-20 Te Rarawa Ohaeawai/Okaihau 32-31 Eastern Awanui 32-0 Panguru
South Zone: Whangaruru beat Southern by default Pipiwai beat City by default Moerewa/UK 64-5 Otiria Tomarata 44-5 Mangakahia Kaihu 63-5 Ruawai