De Ligt's move away from Ajax is set to be one of the biggest deals of the transfer window, with the 19 year-old having been linked to a number of Europe's biggest clubs.
Serie A champion Juve appears the team to secure the centre-back's prized signature, however, for a reported fee of €66million.
Ajax confirmed that De Ligt had been left out of its travelling squad for a pre-season trip to Austria, and Overmars believes the transfer is all but done, with the player expected in Turin to undergo a medical on Wednesday (AEST).
"The end of the transfer of De Ligt is near," Overmars said. "We're awaiting bank guarantees, because we are very strict with this at Ajax. Hopefully things will progress, but I think there will be no further obstructions. They are Italians."
De Ligt will leave a big void in Ajax's defence, with the youngster having been instrumental in leading Erik ten Hag's side to the Champions League semi-finals last season.
Mexico international Edson Alvarez could act as De Ligt's replacement, though Overmars insists the Club America centre-back would have been a target regardless.
"This transfer is not depending on the development of De Ligt's transfer," Overmars said. "Edson is a player we think is good, so he might come to us. He is a good age, 21, and plays on a regular basis in the national team of Mexico and we know him very well because we scouted him over a longer period.
"He has progressed very well, and he can play in many positions."