Located at 79 Fitzgerald Ave, the new unmanned 24-hour station started pumping at noon on Thursday. It offers retail and commercial customers unleaded 91, premium 95 and diesel.
A car wash will also be added to the site soon.
Waitomo lowered its prices for 24 hours from noon on Thursday - with unleaded 91 going for $1.959 a litre, premium 95 $2.109 and diesel $1.199.
Waitomo group managing director Jimmy Ormsby said the opening marked the beginning of a new era for the 100 per cent New Zealand owned business.
"A year ago, we announced our intentions to move our expansion plans south, having led competition and choice in the North Island fuel market," he said.
"Kiwis on the mainland deserve to benefit from the price competition we’ve been driving - and we’re delivering on that promise, just in time for Christmas.
"Regionally motorists in the South Island, like Kiwis in Wellington, have been paying a higher price for their fuel, and that’s not the Kiwi way.
"Our expansion into Wellington this year resulted in a significant price drop across all brands, so let’s see how we can stir things up down south.
"The opening means a lot to our team and to the Ormsby family. We’re a lean, low-cost family business, but we’ve shown we can deliver - opening nine new sites this year alone.
Established in Te Kuiti, King Country, more than 70 years ago by Desmond Ormsby, Waitomo Group now has 65 sites.
The company plans to open a number of new sites throughout the South Island next year.
