Thailand's influential former Prime Minister Thaksin Shinawatra has been released from prison, after about eight months behind bars following a court ruling that deemed he had wrongfully stayed in hospital to avoid jail time.

The 76-year-old billionaire has remade and dominated Thai politics for a quarter-century, but his influence has waned of late following his jailing and his once formidable Pheu Thai Party's worst election performance on record earlier this year.

With his hair closely cropped and in a simple white shirt, Thaksin walked out of prison around 7.40 am local time and was immediately surrounded by family members, including his daughter, Paetongtarn Shinawatra, who was sacked as prime minister by a court order last August.

Hundreds of supporters who had thronged outside Bangkok's Klong Prem Central Prison since the early hours of Monday chanted "we love Thaksin" as he greeted them on his release, having served about two-thirds of his sentence before being paroled.

After 15 years in self-exile, Thaksin returned to Thailand in 2023 to face an eight-year sentence for conflicts of interest and abuse of power while prime minister from 2001-2006.

This was later commuted to a one-year term by the king.

However, he spent only a few hours in prison before being moved to a hospital VIP wing, citing heart trouble.

In September last year, the Supreme Court ruled Thaksin must serve that time in prison, concluding he and his doctors had intentionally prolonged his hospital stay with unnecessary surgeries.

He is now required to wear an electronic ankle monitor for the remainder of his sentence.