Defender Pieters, 34, was the only senior recipient of a new contract from Baggies head coach Carlos Corberan as Jake Livermore, Tom Rogic and Kean Bryan all departed.
The former Stoke and Burnley left-sided defender has impressed fans and onlookers with his consistent and versatility this season, mostly in a more unfamiliar centre-back role – and Johnson, 49, co-commentator on WBA Radio, sees it no differently.
"Yes I do (think it's the right call), he's played the majority of the season, he was a free transfer, you've got to say that's a success story," said Johnson, who played 143 times for the Baggis between 2001 and 2006.
"I think he's done really well, I like him, he's a no-nonsense defender and he's versatile, can play in a back three or a central two, left-sided so gives us balance.
"As we all know as we get older your legs go a little bit. In a foot race he might lack a bit but his experience usually puts him in a position where he doesn't get done, because he reads the game really well.
"For me it was an absolute no-brainer, he's given everything and earned that, one of the players who has actually given everything on the pitch."
Pieters played 36 times – including 34 starts – all in the Championship after checking in as a free agent following the closure of last summer's window. He was required in the heart of Albion's defence due to lengthy absences for Semi Ajayi and Kyle Bartley.
"As an older defender you should be able to play across the backline, it shouldn't be a problem, he's decent in the air and reads the game well," Johnson continued. "I think he's been decent.
"A few might have criticised him, you're not going to be everyone's cup of tea. I think he's been solid.
"It's not just that (his age), fans want to be excited by a signing, sometimes you've got to look at that experience, he has a lot of knowledge. He's not come in just for his knowledge, to help younger ones, it's to play and he has done that. Hats off to him."
Corbera is plotting a Hawthorns rebuild this summer but, with limited funds due to a lack of investment from Guochuan Lai, will have to rely on affordable deals.