The Nerazzurri president confirmed to reporters on Thursday that a deal for the Manchester United centre-back is close to completion
Vidic said earlier in February that he would leave United once his contract had expired and Goal revealed that the Serbian, who spent eight years at Old Trafford, has agreed to join the Nerazzurri on a two-year deal in the summer.
Thohir confirmed to reporters on his arrival in Italy on Thursday that a deal is very close to completion, which would see the 32-year-old join the San Siro side.
"Vidic? I can not say more than that it is 90 per cent done. When everything is completed we will make an announcement. Do not make me say anything that is not concrete yet," he said.
Vidic had been linked with a number of interested clubs including Juventus, Galatasaray and Monaco, but Inter's general manager Piero Ausilio has been in close contact with the defender's representatives and attended the Premier League clash between Manchester United and Arsenal, where a gentleman's agreement was struck.
Meanwhile, Thohir reflected on Inter's return to winning ways following a poor start in 2014.
He added: "We've taken maximum points in the last two games; the team is good at this time, the team is more balanced. Thanks to Walter Samuel the defence has become more solid, and with Hernanes we have more solutions."
Fifth-placed Inter are gearing up for their clash against Cagliari on Sunday.