On Saturday the three lese majeste convicts were included in a royal pardon that saw over 100 female prisoners released from a Bangkok jail.
"Three women prisoners who were jailed for lese majeste were freed today," Weeranan Huadsri, from the Thai Lawyers for Human Rights, told AFP.
They included Daranee Charnchoengsilapakul, an activist sentenced to 15 years in 2011 for speeches delivered at political rallies.
Known as "Da Torpedo" for her hard-hitting rhetoric, the activist was a fervent supporter of ex-premier Thaksin Shinawatra.
Porntip Mankong, a 29-year-old activist arrested in 2014 for her role in a satirical play, was also released Saturday, the lawyer said.
She had around two months left of her 2.5 year sentence.
The young activist was prosecuted alongside Patiwat Saraiyaem, a male university student who also participated in "The Wolf Bride" play.
Patiwat was released earlier this month after receiving a royal pardon on Queen Sirikit's birthday.
The third lese majeste prisoner set free Saturday was Thitinan Kaewjantranont, an elderly woman jailed for insulting a portrait of the Thai king.
The court that sentenced her in 2015 noted she suffered from mental health issues but said her behaviour was "so evil" it warranted jail time.