His first one was via a pushover scrum where he dived between number No8 Dan Edlington's legs to score.
Hardy's second came from a beautiful flick pass from first-five Jayd Kapa.
Kapa was a standout for the visitors as he used his educated right boot to kick OBM into handy territory all game and convert scoring opportunities.
With the score 25-5 at halftime, the result was almost inevitable.
To Mid Northern's credit they toiled valiantly throughout but were unable to break the defending champions.
OBM coach Mark Kapa said he wasn't expecting the first-half performance his side produced.
"We prepared well this week. The conditions suited us a little better, it meant we could attack up the middle," he said.
"I'm very happy with the performance today and it'll be great to get to back up the title we got last year.
"I couldn't have asked for a better start. We knew they were going to come back in the second half and play some sporting rugby but we dealt with that well."
Meanwhile, Kamo came from behind to pip Waipu 30-25.
In front of a raucous Kamo crowd, Waipu started well to hold a slender 15-13 lead.
Kamo had been the form team all competition but they needed something special to gain a finals berth.
Led well by skipper Nick de Ridder, Kamo fought back well in the second spell and proved why they were the top qualifier.
The likes of prop Jackson Brott, first-five Ethan Bracey and centre Jayden Gravatt all performed strongly for the Magpies as they withstood a spirited and skilled Waipu side.
Waipu showed they were close to making the mark and come next season will be right in the mix again.
The result sets up a blockbuster finals rematch where Kamo will be looking to gain revenge after going down 22-13 to OBM last season.
The final will be played at Toll Stadium.
