The bail was set at Bt500,000. She was released on condition that she must not instigate riots, involve in political movements or leave the country.
Police earlier denied her bail request. She was charged of insulting the monarchy and violating the Computer Crime Act.
Patnaree's arrest sparked heavy criticisms against the junta. The Thai Academic Network for Civil Rights (TANC) warned yesterday that charging Patnaree with lese majeste could provoke hatred among the public. Human Rights Watch also said the junta has "sunk to a new low".
Sirawith is a key member of Resistant Citizen, an anti-junta group.
While his mother is to be released in the evening, Sirawith plans to join New Democracy Movement's "Free Day Say Freedom" activity at Thammasat University this afternoon.
An officer from Chanasongkram Police Station said the event would be recorded and charges would be filed if any violations were spotted.