“We have signed with Thohir,” Moratti said. “The history of Inter welcomes a new season.
“The enthusiasm and pragmatism of new partners are a guarantee for the future.”
The club said in a statement that Thohir and his International Sports Capital (ISC) group had acquired a 70percent stake in the club.
Thohir said: “I’m honoured that Massimo Moratti has entrusted me with the responsibility of guiding Inter to a new chapter, and I am very happy that he continues to be present as my partner.”
The Indonesian billionaire said he had bought “one of the most respected clubs in the world … I am an entrepreneur, but above all a tifoso and sports lover. I’m eager for us to put our passion and international experience to the service of this fantastic club.”
Thohir had been linked with a takeover of the Serie A side since last season, which Inter finished in a disappointing ninth place, failing to qualify for European competition in the process.
Moratti and Thohir met twice, in May and June, this year but failed to reach agreement.
Inter, the last Italian side to win the Champions League, in 2010 when they won the treble under Jose Mourinho, are reported to be desperate for a move away from the San Siro ground they share with city rivals AC Milan.
Moratti is also keen for the club to take advantage of ripe markets in Asia which English Premier League giants like Manchester United have exploited.
Inter are one of the three biggest clubs in Italian football, along with city rivals AC Milan and champions Juventus.
Founder of of the Mahaka Group, 43-year-old Thohir made his fortune in the media and entertainment industry. He owns television, radio and print and internet newspapers and in sport already owns Washington DC United soccer club.
ISC is owned by three Indonesian businessmen – Thohir, Rosan Roeslani and Handy Soetedjo.
Moratti said that a change in management and the appointment of eight members of the club’s Administrative Committee should not be ratified before an extraordinary general meeting in November.
According to Italian media reports, the Administrative Committee should consist of five seats for the Indonesian group and three for the Moratti family.
Moratti, who succeeded his father as head of Inter in 1994, is expected to remain on as club president.
“I don’t know yet,” he said, “but I think it depends on me.”
Inter, currently fourth in the league, become the second Serie A club in the hands of foreigners after the sale of AS Roma to Americans Thomas DiBenedetto and James Pallotta in July 2011.