Chester, 38, was appointed Trinity coach last March and guided them to the semi-final of the Challenge Cup and Super League safety.
The former Hull KR coach's new deal will see him remain at the club until the end of 2019.
"The negotiations were very easy and over quite quickly, we both have the same thoughts of how we want the club to progress," he said.
Trinity are eighth in Super League, with three wins from their opening six games.

The group is managed by Hong Kong's Argyle Street Management and funded by Indonesia's Sinarmas Group, which is managed by Indonesia's Widjaja family.
The offer values Asia Resource Minerals at Â£98.8m and includes plans to inject $150m equity in the embattled company.
British financer Nat Rothschild submitted an alternative $100m refinancing plan in April.
Asia Resource Minerals, formerly known as Bumi, is grappling with tumbling coal prices and a continuing battle for control of the company.
It was founded in 2010 by Nat Rothschild and Indonesia's wealthy Bakrie family.
The co-founders fell out and the company was broken up in March 2014 and renamed Asian Resource Minerals.
The Argyle-Sinarmas bid for the company once again pits Mr Rothschild against a powerful Indonesian family.
The potential acquirers have stressed the importance of "an experienced and proven Indonesian partner", to lead the company. Foreign ownership of businesses is a contentious topic in Indonesia.
Asia Resource Minerals controls nearly 85% of Indonesian coal mine operator Berau. The country's energy minister said on Thursday that it would prefer Berau to be locally owned.
"Berau Coal is a corporate matter between shareholders. But as a policy matter, we want coal to be the pillar of our energy security. The more national mines that are controlled by national firms, the better," said Energy Minister Sudirman Said.
Wakefield coach Chris Chester has signed a new two-year deal.
[NEXT_CONCEPT]
A group of Asian investors has submitted a bid to acquire Indonesian coal miner Asia Resource Minerals.