The 20-year old had a contract with soccer giants Manchester United before ultimately making the move to Australia to follow his dream of playing in the NRL.
He made his debut with the Broncos in Round 16 last year and became a favourite early on.
Farnworth has played 12 games this year for the Broncos on the wing and in the centres and is looming to be a pivotal piece in their backline moving forward.
Coach Anthony Seibold was pleased with the re-signing and loves Farnworth’s work ethic.
“Herbie’s re-signing is great for the club, he has a really strong work ethic and a lot of potential,” he told the club website.
“His journey from the UK to Australia is a terrific story and he has shown a lot of resilience and perseverance over a number of years to create the opportunity he has at the Broncos.
“Herbie has also shown fantastic commitment to us when there was high levels of interest from other clubs, and he should be applauded for that loyalty.”