The former Southland back, who is in the Māori All Blacks' squad to play Ireland, had a stellar season for the Hurricanes in 2022.
Not only did he score nine tries for the side in 10 appearances, including a hat-trick against the Fijian Drua, he broke the Hurricanes record for the most tries scored in a debut season.
Moorby, 23, from Te Awamutu and a product of Hamilton Boys' High School, debuted in Bunnings Warehouse Cup rugby for Southland, said, "I've learnt a lot in the [Hurricanes] environment this year, so I'm looking forward to building on that.
"I can't wait to get stuck in and show what we are capable of in 2023."
Hurricanes coach Jason Holland said, "Moorby was one of our final signings last year. We were excited by a couple of little bits we saw back then, but he's come in with an unbelievable attitude to getting better.
"He wasn't in our starting group at the beginning of the year, but he's taken every opportunity thrown his way.
"He's achieved some awesome things for a guy in his first year of Super footy, and he's going to be a big part of what we do.
"Selection at 15 [fullback] in the biggest games, at the business end of the season, shows where he's got to. He was doing some awesome things for us, adjusted his game to fit into how we wanted to play, and got rewards for that.
"Moorby is an awesome signing, an awesome man, and we're happy for him," he said.