The 24-year-old, capped 10 times for his country, is presently with Standard Liege but had a spell with Belgian Pro-League rivals Kortrikj.
Injury has hampered the left-sided centre-half's time in Belgium and he last played for Standard Liege in July.
Gershon's agent, Dudu Dahan, said: "When a club like Celtic asks you to come, you get on a plane and come."
Celtic will have to do without Efe Ambrose for much of January should the central defender make Nigeria's final squad for the forthcoming Africa Cup of Nations.
Should Nigeria progress to the final, Ambrose would not return to Scotland until after 5 February.
It is understood that Gershon and his agent will discuss the possibility of a permanent or loan deal with the Scottish champions.
On his arrival at Glasgow Airport, Gershon told STV: "I am very happy to be here. I am very excited to have the opportunity to play for Celtic.
"I just hope that everything will be done tomorrow and then I can speak more."
Gershon admitted he had not yet discussed the possible move with Celtic midfielder and fellow Israeli Beram Kayal.
"I haven't spoken to him yet," he said. "He is a good friend of mine, but everything was very quick, so I didn't find the time to speak to him.
"But, in the past, he has told me only good things about Celtic."