Recruited from Ligue 1 side AS Saint-Étienne earlier this month, the defender signed a five-year deal at King Power Stadium, becoming the Club's third summer signing following Belgian international full-back Timothy Castagne and Turkey winger Cengiz Ünder.
Fofana could potentially make his Leicester debut when the Foxes return to action for Sunday's home fixture with Aston Villa (7:15pm BST kick-off).
Johnson believes City's new No.3 has the playing style required for the Premier League and expects him to be able to cope with the physicality of the English game.
"For me he's a very exciting defensive talent, one of the brightest to come out of Ligue 1," Johnson told LCFC.com.
"Like William Saliba and Kurt Zouma before him, we're seeing a player of real great promise leaving France very early in their career.
"I think that Fofana has potential to go on and establish himself in the way that Zouma has. Yes, he's still very young, but he's not had any physical issues yet.
"He's riding on the crest of a big wave of positivity, he's got good momentum coming into this move.
"I think he will bring the right sort of physicality and technique that will be needed to succeed in the Premier League."
After making his professional debut for Les Verts in May 2019, he went on to play 25 times for the Ligue 1 outfit, before sealing his move to the Foxes.
Given his personal character, Johnson expects Fofana to take this new challenge in his stride and not let his rapid rise adversely affect him.
"I think he's ready to make the step up, he'll obviously be very keen to impress," he continued. "Expectations are high and he'll want to show that he can live up to it.
"He's young, he's very eager to learn, he's very ambitious. From a young age, his desire and one of the main goals in his career would be to play in the Premier League, so he'll be realising that ambition very early on.
"He's very determined, very motivated and for me he has the makings of someone who you can really build the defensive unit around."
Johnson believes that Fofana can be categorised as a late bloomer, who will continue to improve as he gains more experience at the highest level.
"He doesn't have the youth academy background that a lot of the French players that move to the Premier League have, in spending the bulk of their formative years with just one big club," Johnson said.
"He went around a couple of sides before settling with Saint-Étienne. It's interesting that they seem to have an eye particularly for defenders.
"It reflects well on them that they recognised him and brought him into their academy, but equally, it reflects well on Fofana that he caught their eye, considering that they specialise in developing very good, tried and tested centre-backs at continental level."
The-19-year-old made his France Under-21s debut in a 5-0 victory over Liechtenstein last week and followed it up with another clean sheet during a 1-0 win over Slovakia.
According to Johnson, Fofana has all the attributes to be a success on the international stage in the future, despite not playing for Les Bleus' younger age groups.
"Given the way he performed in the last six to 12 months, it was expected, it wasn't a huge surprise," Johnson said of Fofana's call-up.
"I also think it's logical he would be called up for the Under-21s, if you look at his age and the fact that France at senior level are spoilt for choice when it comes to central defenders.
"Playing with the Under-21s side at the moment is more in line with what would be good for his development and it's a good way to get used to international football.
"It's a very talented crop of players and I think it will stand him in good stead moving forward that he's had a taste of the international setup before potential involvement at senior level."