Picked up as a forward in the 2005 rookie draft, Grundy kicked three goals on debut, but struggled to establish himself in the front half of the ground.
A total of 24 games over his first three seasons on the senior list was a modest return, but he was moved into defence full time in 2009 and hasn't looked back since.
Grundy, who turned 28 on Monday, has missed just five games over the past six years and will earn Life Membership of the Swans when he plays against the Suns.
"It's been a little while coming, but the last couple of weeks it's been in the back of my mind a little bit," he told reporters on Wednesday.
"I'm very proud to play 150 games for this club.
"I had to do it pretty hard early on and had a bit of a slow start to my career, but to be able to secure my spot in the senior side and finally get to 150 feels great and hopefully there's a few more to come.
"The club has been great to me and gave me time to develop and I always took that into account over the years.
"Hopefully I've been able to repay the club with some good games of footy."
A quiet achiever who doesn't always earn the plaudits afforded to some of his higher profile teammates, Grundy is still given assignments on some of the competition's best forwards each week.
"He's a guy that took four or five years before he established himself at League level," Swans coach John Longmire said.
"Coming off the rookie list and working really hard at his game, it took him a long time to get on the senior list.
"He played as a forward initially and then took a few more years before we put him back and he started to feel really settled.
"He plays consistently well now as a key defender and is an important part of our team."
Grundy credits Tadhg Kennelly, Craig Bolton and Leo Barry with helping him with his transition as a defender, while his partnership with Ted Richards is one of the best in the AFL.
The Swans own the League's best defensive record so far this year, conceding just 697 points over 10 games, ahead of Fremantle (711) and Port Adelaide (760).
With key forwards Charlie Dixon, Sam Day and Tom Lynch to contend with this week, Grundy knows they face another tough assignment on Sunday.
He also feels Gold Coast are fully deserving of their 7-3 record.
"They've had a really good year and they've got some good key forwards," he said.
"They're all pretty mobile, myself and Teddy will have our work cut out again this week, and hopefully we can have a good team effort and come away with the win.
"We're halfway through the season and to be sitting where they are, you don't just get there on luck.
"We're going to have to take them pretty seriously this week or else they'll get over the top of us."
