The SPL champions have the option to buy the player at the end of his temporary spell, with a three-year contract having been agreed should they exercise that option.
The Israeli defender travelled to Scotland last week ahead of a switch from Belgian side Standard Liege. He underwent a medical at the weekend.
Gershon requires a work permit to conclude his move and will travel to Brussels shortly to switch his visa, before linking up with Neil Lennon's side at their training camp in Spain this week.
"I'm very happy to get a club of this size and I'm primed and ready for the challenge," Gershon said on his agent's Facebook page.
Dahan added: "Everything was closed to the satisfaction of all parties. The only issue that remains now is getting a work permit.
"That should be settled next week. Rami will travel to Brussels to sign paperwork and will then travel to Celtic's training camp in Spain."
Celtic are yet to make an official announcement on the signing of Gershon.
Dahan posted a picture of himself and Gershon signing his contract with the club on his Facebook page.