The Netherlands international has become one of the most sought-after players in world football, with numerous elite clubs tracking his progress at the Dutch giants.
Goal understands that both Barca and City have registered their interest in signing the 19-year-old, who would cost upwards of €50 million (£43m/$57m), and that the Premier League champions began laying the groundwork for a move towards the end of last season.
Barca see the player as the next Gerard Pique, but De Ligt is under contract until 2021 - with Ajax having the option to extend that for a further year - and appears in no rush to make a decision over his future.
Juve's interest, however, may complicate matters for both Barca and City, with the club working alongside agent Mino Raiola to negotiate a price for De Ligt.
The Serie A giants are keen to bolster their defensive ranks, with Andrea Barzagli set to leave the club at the end of the season, and Medhi Benatia and Daniele Rugani potentially expendable.
Juve's sporting director Fabio Paratici has thus identified De Ligt as the best possible purchase option in either January or next summer, though both the Italian side, and Barca, would struggle to match the financial muscle of Pep Guardiola's City.
De Ligt is highly-rated across Europe, and Ajax CEO Edwin van der Sar, the former Manchester United goalkeeper, waxed lyrical about the potential of the defender earlier this year.
"He looks like he’s been doing this for six or seven years," Van der Sar said in an exclusive interview with Goal. "Matthijs is very mature for his age: he has the physique of a 24-year-old.
"He is also strong with both feet, has an extremely good range of passing, can head the ball, scores goals and is a real leader at the back already at the age of 18.
"He came into the first team last year and has never looked back."
De Ligt is already Ajax captain, and has played 14 games for the club this season, while he has also won 11 caps for the Netherlands.
As reported by Goal, Barca and City are also going head-to-head for one of De Ligt's Ajax team-mates, Frenkie De Jong, with both sides believing the other has the advantage in negotiations.