The Temora product will remain with the Red V until at least the end of the 2025 NRL season after signing the longest deal in the club's history.

The 20-year-old had attracted plenty of interest from rival clubs but elected to remain with the club after coach Paul Gregor recently confirmed Lomax would get first crack at the Dragons' No.1 jumper next year.

Lomax said he was delighted to re-sign with St George Illawarra.

"Being able to go back to Temora at Christmas knowing that my future is settled and that I'm definitely going to be a Dragon for a while yet is very exciting," Lomax told My family and I are very happy with the decision that's been made," he said.

"With 2020, I've attacked every session possible and soaked up as much information as I can when it comes to playing fullback. I realise I still have a lot to learn but it's a challenge I'm really looking forward to."

Dragons recruitment chief Ian Millward said Lomax was a "significant retention" for the club's on-field fortunes and succession planning.

"There was a lot of speculation over Zac with numerous clubs in for him and we respected the process he and his management went through," Millward said.

"One thing that hit home over the past couple of weeks was that he wanted to be a Dragon and wanted to stay at the Dragons.

"To have him recommit long term is a no-brainer. Our aim now, and Zac's, is to have him wear the Red V for the rest of his career - he wants to be a one-club player.

"Zac is already the benchmark at training. With his attitude and attention-to-detail we see him as a future leader of our club. The cherry on top is he's an outstanding goal kicker so we are pleased to shore that up too."

The club has also announced Lomax's younger brother Hayden has signed a one-year development player contract extension.

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