Hook played key roles in the region's 2007 and 2010 triumphs, featuring in 15 games in each of those title-winning seasons.
And just as his own reputation has continued to rise, the versatile Lions tourist has seen the tournament grow massively during his time with the Ospreys.
Having won his first Celtic crown against the Borders in front of a small crowd at Netherdale, Hook was watched by 19,500 people when he picked up his second winners medal in Dublin in May of this year.
For Hook, the standard, intensity and excitement of the league is increasing every year and he and everyone else at the Ospreys is proud to be able to be able to call himself a Magners League Champion.
Here's what James had to say about last season's Grand Final triumph; the new Play-Off system; the quality of the Ospreys squad; the challenge of European rugby, and his move from fly-half to centre…
James on winning last season's inaugural Grand Final
"We take the Magners League very seriously and that's shown by the three titles we've won so far.
"The way we won the title last season away to Leinster in the first Grand Final was massive for us. It's a big step for us going forward.
"The fact that it was a Grand Final and it was away from home definitely made it more special. I don't think many people gave us a chance over there.
"We went there on the back of Leinster having just been knocked out of Europe so the Magners League was all they had left, too. They put everything into the game but we gave it that little bit more and deserved to win in the end.
"It was different winning it this time. They guys on the loudspeaker before the game really bigged it up; we had dancers and singers before kick off and it was like a mini international.
"The boys really enjoyed it. The weather was nice, too, and it all made for a great occasion. And that occasion was even better because we won."
On the introduction of the Play-Off system
"I can't speak for all the boys but I really enjoy it. It gives you something to aim for at the end of the season and, if you don't finish at the top of the league, you're still in with a shout. We didn't have a home draw in the final but, as long as you're in the mix, you can still win it.
"There was always a lot on every game. I think Cardiff Blues showed that. They were down towards the bottom end of the table for most of the season but, right at the end, they were really close to getting into the Play-Offs.
"It's a really competitive competition and the league went down to the final round last season.
"It's getting bigger. It's building and it's definitely going in the right direction. The Ospreys have always taken the Magners League seriously, just as we do with Europe. We've won it three times and we'll aim to do it again next year."
James was a try scorer in the Play-Off win over Glasgow Warriors
On strength in depth at the Ospreys
"Since I've been here, the squad's got stronger every single season. We haven't made any high-profile signings this summer but the signings we have made have been effective and there's a reason for them.
"You just have to look around the team and see that every person is a class player. There was no need to strengthen the squad even more because we've got the players here."
On taking their Magners League success into Europe
"It has been difficult losing in Europe. We've been knocked out in the quarter-finals three times now and they're such great occasions. But the more we play in those occasions, the better we're going to get.
"Beating teams like Leinster and Munster away last season in the Magners League will stand us in good stead. We've got to take all these experiences and use them positively to keep fighting this season.
"I think that's the main thing. We go to Munster but we won't fear them because we know they can be beaten; other teams have beaten them and we've beaten them. It's a mental thing but that's what sport is most of the time.
"If we can take the experiences of last year into this year, I think we'll be alright."
On playing the majority of last season at centre
"It took a little bit of time to adjust but I enjoyed it. I'm now aiming to get back fit and on the field for the Ospreys and, hopefully, put myself in contention for Wales.
"There's not really been any discussions about positions. Dan (Biggar) did well last season at 10 with myself at 12 and Bish (Andrew Bishop) at 13. But that's the coaches' decision and I'll listen to them and do what they say.
"The season did end nicely, both internationally and with the Ospreys. I really enjoyed it, especially the back end of the season over the last four or five months. Hopefully I can take that form into the new season and carry on where I left off."
For more from James throughout the season, keep your eye on the Ambassadors section of this website.
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