He said he would beat what he called politically motivated corruption charges from the years he was in power. The 58-year-old billionaire businessman surrendered to police at the airport to be taken to the Supreme Court.
He was removed from power in a military coup in September 2006 and has lived outside the country since then.
Mr Thaksin is expected to be released on bail on two separate charges.Speaking to the BBC's Andrew Harding on the flight from Hong Kong, Mr Thaksin said he wouldn't be seeking revenge against the coup bosses who forced him out of power after five years in office.
He said he had mixed feelings about returning to home, but that he had finished with politics and wished to focus on his football interests - he owns Manchester City and was travelling with two of the British club's players.
His party, Thai Rak Thai, was outlawed following the coup and he was personally banned from politics for five years but his opponents fear he has returned to influence events from behind-the-scenes.
Many of Mr Thaksin's followers formed the People Power Party (PPP), which won elections in December last year.