As the Knights chase consecutive victories for the first time this year, O'Brien reaches the milestone just four games into his fifth season as an NRL head coach

Only last week, the former Storm and Roosters assistant became Newcastle's second-most capped coach, surpassing the club's first premiership-winner Malcolm Reilly, who coached 98 games between 1995-98.

O'Brien will now join 2001 title-winner Michael Hagan as the only other coach to have reached a century.

"To coach 100 NRL games at one club is a terrific achievement," Knights football director Peter Parr said.

"He's played finals three of his first four years here. It's something he should be very proud of. To coach 100 NRL games at the Knights, and only second behind 'Hages', it's a significant milestone."

Hagan oversaw 155 matches - including the 2002 World Club Challenge - through 2001-06. He began his tenure in his late 30s, a few years younger than O'Brien and with far less experience.

He uniquely won a premiership in his first season, but credited the support of club officials and strong player leadership for his lengthy stint, which he believes O'Brien is now gaining.

"From chairman, CEO, footy manager, certainly if I look at my time I had the benefit of that in those first 100 games," Hagan said.

"I was young too, so I needed that support around me.

"I think Adam has probably got that now a bit with Peter Parr in his corner, and there seems more stability around their group in terms of retaining their best players.

"They've got the nucleus of a pretty good senior playing group, and I think Adam has worked really hard on that the last year or two.

"Leadership for Kalyn Ponga, Jayden Brailey and a couple of others that have come in ... That's something all good coaches seem to have, some senior players that can help you run the team."

Parr joined the Knights towards the end of O'Brien's third season, but said the coach had developed in key areas the past couple of years.

In 2022, the Knights ran third-last, dealt with a couple of off-field incidents and last year O'Brien was dealing with the loss of his mum but managed to steer the side to their best finish since 2006.

"If you're going to be an NRL head coach, you have to be prepared to ride the roller-coaster," Parr said.

"It's a very heavily scrutinised job, and that sort of scrutiny can be taxing on you as a person.

"I don't think there's any doubt about his coaching ability.

"He's a very good coach, gives very good clarity to his players and has a really high care factor.

"You have to be very good at handling some adversity, because it's never far away if you're a head coach.

"I think he has learnt to handle that side of the business a lot better, along the journey, as you would expect."

Still involved in the game as a radio commentator of Knights games and a mentor to Cowboys coach Todd Payten, Hagan said there was far greater scrutiny today than in years gone by.

"It's probably changed tenfold [in terms] of opinion and news cycles, social media," he said.

"The actual coaching, I reckon, the footy part of it, is actually quite straightforward and in the end that's what you've got to focus on and try and ignore some of the other stuff.

"[In] Newcastle, you get plenty of free advice from the punters when you're walking around town, and I think Wayne Bennett summed it up; you've got to be careful not to listen too hard, otherwise you'll be sitting with them soon.

"I think 100 games in the NRL is a fairly monumental achievement."

When O'Brien inked a three-year contract extension shortly before this season, Knights CEO Philip Gardner predicted he would become the club's first coach to reach 200 games.

Hagan hopes O'Brien does eclipse his record, but said the next challenge for the coach and his players was to become a more dominant side.

"Reaching the [top] eight on a couple occasions, being able to do that consistently is one thing, and that in itself is a really difficult assignment given the quality of the other teams," he said.

"And I guess you aspire to be in the top four beyond that.

"That's the challenge for the group and Adam in the next year or two or three.

"And if you're good enough to do that, then you give yourself a genuine chance of progressing further.

"But it's tough going, there's no guarantees and you need an ounce of luck."